Tagged Vaccination and Immunization

¿Ya podemos besarnos con desconocidos?

Una serie de nuevos comerciales muestra besos ensalivados. Los viajes en avión están regresando. Y la inminente vacunación puede parecer un boleto de vuelta a la normalidad para los veinteañeros de Estados Unidos, muchos de los cuales se sienten desesperados por volver a su vida social de 2019 con fiestas abarrotadas y pistas de baile con luz estroboscópica, así como la posibilidad de enviarle un mensaje de texto espontáneo a un amigo: ¿Quieres ir por un trago?

Los adultos más jóvenes han sido de vital importancia en la propagación del coronavirus.

Un informe de los Centros para el Control y la Prevención de Enfermedades (CDC, por su sigla en inglés) mostró que, de junio a agosto de 2020, las infecciones por COVID-19 entre las personas de 20 a 29 años aumentaron y representaron más del 20 por ciento del número total de casos en el país. Poco después, los datos mostraron que esos casos provocaron un aumento en los contagios entre personas de mediana edad y mayores, lo cual pudo haber contribuido al incremento nacional de casos en Estados Unidos.

Ahora, a medida que se ha dado prioridad a la vacunación de personas de la tercera edad y alrededor de dos tercios de los mayores de 65 años ya recibieron al menos una dosis de la vacuna, su riesgo de enfermar de gravedad tras contagiarse por un joven ha disminuido de manera considerable.

Pero eso no significa que sea completamente seguro ir de fiesta como si fuera 2019.

La forma de calcular el riesgo de transmitir el virus a personas más vulnerables dependerá de tus circunstancias individuales: si vives con tus padres u otros veinteañeros, si hay personas con riesgo de padecer síntomas graves de COVID-19 en tu círculo social. “No hay una simple luz roja o luz verde”, afirmó William Schaffner, experto en enfermedades infecciosas de la Universidad de Vanderbilt.

A continuación, algunas respuestas a preguntas habituales sobre qué pueden hacer los jóvenes que presentan un bajo riesgo en general después de vacunarse.

¿Se puede volver a la normalidad así como así?

Nos dirigimos hacia una especie de normalidad, subrayan los expertos, pero todavía hay muchas incógnitas sobre qué pasará en los próximos meses. Aunque el aumento de las tasas de vacunación y el descenso de los casos son alentadores, explicó Schaffner, hay tres situaciones que podrían obstaculizar o anular ese progreso: si la gente se niega a vacunarse, si las tasas de transmisión comunitaria siguen siendo altas y si las variantes del virus disminuyen la eficacia de las vacunas.

“Si los adultos mayores y los más jóvenes se vacunan, y las variantes no son demasiado variantes, entonces podríamos tener muchas fiestas en la piscina”, dijo. “Los bares podrían abrir”.

“La vuelta a la vida normal debería ser un lento proceso gradual”, comentó Tara Kirk Sell, asociada principal del Centro Johns Hopkins para la Seguridad Sanitaria, que investiga eventos sanitarios a gran escala. Recomendó que la gente escoja una actividad de mayor riesgo que haya querido realizar durante la pandemia —como ver a los amigos o salir a comer— y la lleve a cabo para celebrar su vacunación. “Estamos hablando de un avance gradual, en lugar de actuar como si estuviéramos cantando ‘Libre soy’”, dijo.

Lelanie Foster for The New York Times
Lelanie Foster for The New York Times

Sin embargo, gran parte de esto depende de la cantidad de virus que circule en tu comunidad.

“Una vez que se llegue a una combinación de casi ningún caso en la comunidad y un alto porcentaje de gente vacunada; entonces, todo cambia”, afirmó Paul E. Sax, especialista en enfermedades infecciosas en el Brigham and Women’s Hospital de Boston. “De hecho, eso es lo que esperamos. Ahí es cuando dices: ‘Claro, me arriesgaré a ir a un restaurante. Mi probabilidad de ir a un restaurante y enfermar de COVID-19 no es mayor que el riesgo de enfermar de un resfriado normal’. Es un riesgo que la gente debería estar muy dispuesta a correr”.

“La gente tiene que estar atenta al entorno de la COVID-19 del mismo modo que lo está al clima”, comentó Peter Chin-Hong, experto en enfermedades infecciosas de la Universidad de California en San Francisco. Recomendó que la gente vigile las tasas de vacunación en su comunidad y los casos por cada 100.000 habitantes. Carlos del Río, especialista en enfermedades infecciosas de la Universidad Emory, recomienda el sitio Covid ActNow para consultar el número de casos por condado; The New York Times también da seguimiento al nivel de riesgo por condado.

Si te encuentras en una zona que tiene menos de 10 casos por cada 100.000 habitantes, es más seguro ir a una fiesta o socializar al aire libre en un grupo mayor donde todos estén vacunados. Un escenario mucho menos seguro sería participar en el tipo de fiestas relacionadas con las vacaciones de primavera que están atrayendo la atención en Florida, que registró 22 casos por cada 100.000 habitantes en los últimos siete días y se piensa que tiene una concentración importante de B117, la variante más contagiosa y tal vez más letal del virus identificada por primera vez en el Reino Unido.

¿Podemos besarnos con desconocidos?

Los expertos entrevistados para este artículo dijeron que besarse y tener otro tipo de contacto íntimo con desconocidos tras vacunarse puede ser seguro siempre y cuando puedas confirmar que la otra persona también está vacunada.

Incluso sin esa confirmación, puede que besarse con un extraño sea una actividad de menor riesgo que ir a un lugar abarrotado como una discoteca o una fiesta, afirmó David Rubin, profesor de Pediatría de la Facultad de Medicina Perelman de la Universidad de Pensilvania. “Es una de esas cuestiones que se dejan a criterio de cada persona, sin juzgar”, comentó.

“Si estás en un entorno controlado y solo te encuentras con esa persona y quieres asumir el riesgo de besarla y crees que esa persona no parece tener ningún riesgo de padecer COVID-19 grave, conforme a los lineamientos de los CDC, adelante, puedes hacer todo lo que quieras con esa persona”, comentó Chin-Hong.

Si estás vacunado, pero no puedes confirmar la vacunación o la condición médica de la otra persona, aun así, no habrá problema para la mayoría de los jóvenes, agregó.

“La cuestión aquí es el control”, continuó. “Cuantas más narices y bocas se junten, más riesgo potencial de transmisión”.

También está el evidente dilema logístico: puede ser difícil verificar de modo casual y rápido que alguien recibió todas las dosis requeridas de la vacuna y que es de bajo riesgo. Hace poco, una aplicación de citas, Coffee Meets Bagel, añadió una opción para incluir el estado de vacunación en los perfiles de citas, aunque no requiere verificación.

¿Podemos reunirnos en grupos?

A principios de marzo, los CDC dieron a conocer recomendaciones que afirmaban que era seguro para los adultos vacunados reunirse en grupos pequeños sin cubrebocas ni distanciamiento social. Una vocera de los CDC comentó en un correo electrónico que dichos lineamientos aplicaban a toda la gente que reside en Estados Unidos y que no había consideraciones adicionales para los adultos más jóvenes.

En la práctica, eso significa que no hay problema en que un grupo de entre cinco y diez amigos vacunados se reúnan sin tomar precauciones. Pero cuanto mayor sea la reunión, más probable será que alguien del grupo no esté vacunado. Aunque las tres vacunas que se administran en Estados Unidos (Pfizer, Moderna y Johnson & Johnson) parecen ser eficaces para prevenir los síntomas graves de la enfermedad del virus, aún no sabemos si evitarán que las personas contagien a otras.

¿Qué pasa con los bares en espacios cerrados?

Ashish K. Jha, decano de la Escuela de Salud Pública de la Universidad Brown, predijo que la mayoría de los bares abrirán para el verano en todo el país. También predijo que serán una fuente importante de propagación del virus entre las personas no vacunadas, aunque, en general, deberían ser seguros para quienes han recibido la vacuna.

“La conclusión es que, si quieres ir a un bar, si quieres ir a una discoteca, puedes hacerlo y estarás bastante seguro” una vez que te hayas vacunado, explicó Jha. No obstante, otros expertos advirtieron que todavía hay demasiadas incógnitas (relacionadas con las variantes o si se puede seguir transmitiendo el virus después de haberse vacunado) como para animar con toda libertad a la gente a volver a los bares en interiores.

Los bares al aire libre pueden ser más seguros, dependiendo de su configuración y de si la transmisión en la comunidad es baja. Solo asegúrate de que tu grupo de amigos sea pequeño y no una multitud.

¿Qué pasa con los conciertos al aire libre?

Los expertos coinciden en que los conciertos al aire libre pueden ser seguros, sobre todo si los asistentes usan cubrebocas y se mantienen distanciados. Las actividades al aire libre pueden admitir grupos mucho más grandes de personas vacunadas, comentó Sax.

“La gente se pregunta por qué no hubo más casos después de las manifestaciones del verano. Bueno, se debe a que se llevaron a cabo al aire libre. Será el mismo caso para los conciertos al aire libre, además, me sorprendería mucho que hubiera algún evento de propagación importante vinculado con un concierto en un espacio abierto”.

¿Es necesario que los jóvenes se vacunen?

Los expertos expresaron su preocupación por la reticencia a vacunarse entre los jóvenes. En enero, la Oficina del Censo de Estados Unidos dio a conocer datos de una encuesta que mostraban que los estadounidenses menores de 44 años eran los más renuentes a vacunarse.

“Hemos estado promoviendo la vacuna entre las personas mayores a fin de protegerlas de la hospitalización y la muerte”, afirmó del Rio. “La mayoría de los jóvenes, si se contagian, tienen síntomas leves. Necesitamos poder comunicar de manera muy clara que la vacunación es benéfica para los jóvenes, además de decir: ‘No te vas a morir’”.

“Cuanto más rápido vacunemos a la gente, más probable es que tengamos una vida más normal”, recalcó.

Covid-19 Vaccine Side Effects: Your Questions Answered

The most common questions about vaccination side effects, answered.

Every day nearly three million people in the United States are getting the Covid-19 vaccine. And every new jab prompts new questions about what to expect after vaccination.

Last week I asked readers to send me their questions about vaccinations. Here are some answers.

Q: I’ve heard the Covid vaccine side effects, especially after the second dose, can be really bad. Should I be worried?

Short-lived side effects like fatigue, headache, muscle aches and fever are more common after the second dose of both the Pfizer-BioNTech and the Moderna vaccines, which each require two shots. (The Johnson & Johnson vaccine requires only a single shot.) Patients who experience unpleasant side effects after the second dose often describe feeling as if they have a bad flu and use phrases like “it flattened me” or “I was useless for two days.” During vaccine studies, patients were advised to schedule a few days off work after the second dose just in case they needed to spend a day or two in bed.

Data collected from v-safe, the app everyone is encouraged to use to track side effects after vaccination, also show an increase in reported side effects after the second dose. For instance, about 29 percent of people reported fatigue after the first Pfizer-BioNTech shot, but that jumped to 50 percent after the second dose. Muscle pain rose from 17 percent after the first shot to 42 percent after the second. While only about 7 percent of people got chills and fever after the first dose, that increased to about 26 percent after the second dose.

The New York Times interviewed several dozen of the newly vaccinated in the days afterward. They recounted a wide spectrum of responses, from no reaction at all to symptoms like uncontrolled shivering and “brain fog.” While these experiences aren’t pleasant, they are a sign that your own immune system is mounting a potent response to the vaccine.

Q: Is it true that women are more likely to get worse side effects from the vaccine than men?

An analysis of safety data from the first 13.7 million Covid-19 vaccine doses given to Americans found that side effects were more common in women. And while severe reactions to the Covid vaccine are rare, nearly all the cases of anaphylaxis, or life-threatening allergic reactions, occurred in women.

The finding that women are more likely to report and experience unpleasant side effects to the Covid vaccine is consistent with other vaccines as well. Women and girls can produce up to twice as many antibodies after receiving flu shots and vaccines for measles, mumps and rubella (M.M.R.) and hepatitis A and B. One study found that over nearly three decades, women accounted for 80 percent of all adult anaphylactic reactions to vaccines.

While it’s true that women may be more likely to report side effects than men, the higher rate of side effects in women also has a biological explanation. Estrogen can stimulate an immune response, whereas testosterone can blunt it. In addition, many immune-related genes are on the X chromosome, of which women have two copies and men have only one. These robust immune responses help to explain why 80 percent of autoimmune diseases afflict women. You can read more about women and vaccine side effects here.

Q: I didn’t have any side effects. Does that mean my immune system didn’t respond and the vaccine isn’t working?

Side effects get all the attention, but if you look at the data from vaccine clinical trials and the real world, you’ll see that many people don’t experience any side effects beyond a sore arm. In the Pfizer vaccine trials, about one out of four patients reported no side effects. In the Moderna trials, 57 percent of patients (64 or younger) reported side effects after the first dose — that jumped to 82 percent after the second dose, which means almost one in five patients reported no reaction after the second shot.

A lack of side effects does not mean the vaccine isn’t working, said Dr. Paul Offit, a professor at the University of Pennsylvania and a member of the Food and Drug Administration’s vaccine advisory panel. Dr. Offit noted that during the vaccine trials, a significant number of people didn’t report side effects, and yet the trials showed that about 95 percent of people were protected. “That proves you don’t have to have side effects in order to be protected,” he said.

Nobody really knows why some people have a lot of side effects and others have none. We do know that younger people mount stronger immune responses to vaccines than older people, whose immune systems get weaker with age. Women typically have stronger immune responses than men. But again, these differences don’t mean that you aren’t protected if you don’t feel much after getting the shot.

Scientists still aren’t sure how effective the vaccines are in people whose immune systems may be weakened from certain medical conditions, such as cancer treatments or H.I.V. infection or because they are taking immune suppressing drugs. But most experts believe the vaccines still offer these patients some protection against Covid-19.

The bottom line is that even though individual immune responses can vary, the data collected so far show that all three vaccines approved in the United States — Pfizer-BioNTech, Moderna and Johnson & Johnson — are effective against severe illness and death from Covid-19.

Q: I took Tylenol before I had my Covid vaccine shots and had very little reaction to the shots. Did I make a big mistake?

You shouldn’t try to stave off discomfort by taking a pain reliever before getting the shot. The concern is that premedicating with a pain reliever like acetaminophen (Tylenol) or ibuprofen (Advil, Motrin), which can prevent side effects like arm soreness as well as fever or headache, might also blunt your body’s immune response.

While it’s possible that taking a pain reliever before your shots might have dampened your body’s immune response, vaccine experts say you shouldn’t worry, and you shouldn’t try to get another shot. Studies of other vaccines suggest that while premedicating can dull the body’s immune response to a vaccine, your immune system can still mount a strong enough defense to fight infection. A review of studies of more than 5,000 children compared antibody levels in children who took pain relievers before and after vaccinations and those who did not. They found that pain relievers did not have a meaningful impact on immune response, and that children in both groups generated adequate levels of antibodies after their shots.

The high efficacy of all the Covid vaccines suggests that even if taking Tylenol before the shot did blunt your body’s immune response, there’s some wiggle room, and you are likely still well protected against Covid-19. “You should feel reassured that you’ll have enough of an immune response that you’ll will be protected, especially for vaccines that are this good,” said Dr. Offit.

Q: What about taking a pain reliever after the shot?

“It’s OK to treat” side effects with a pain reliever, said Dr. Offit, but if you don’t really need one, “don’t take it.”

While most experts agree it’s safe to take a pain reliever to relieve discomfort after you get vaccinated, they advise against taking it after the shot as a preventive or if your symptoms are manageable without it. The concern with taking an unnecessary pain reliever is that it could blunt some of the effects of the vaccine. (In terms of the vaccine, there’s no meaningful difference if you choose acetaminophen or ibuprofen.)

During the Moderna trial, about 26 percent of people took acetaminophen to relieve side effects, and the overall efficacy of the vaccine still was 94 percent.

Q: Are the side effects worse if you’ve already had Covid-19?

Research and anecdotal reports suggest that people with a previously diagnosed Covid-19 infection may have a stronger reaction and more side effects after their first dose of vaccine compared to those who were never infected with the virus. A strong reaction to your first dose of vaccine also might be a sign that you were previously infected, even if you weren’t aware of it.

If you previously tested positive for Covid-19 or had a positive antibody blood test, be prepared for a stronger reaction to your first dose, and consider scheduling a few days off work just in case. Not only will it be more comfortable to stay home and recover in bed, the vaccine side effects can resemble the symptoms Covid-19, and your co-workers won’t want to be near you anyway.

Q: I had Covid-19 already. Does that mean I can just get one dose?

Studies suggest that one dose might be adequate for people who have a previously confirmed case of Covid-19, but so far the medical guidelines haven’t changed. If you’ve received the Pfizer-BioNTech or Moderna vaccines, you should plan to get your second dose even if you’ve had Covid-19. Skipping your second dose could create problems if your employer or an airline ask to see proof of vaccination in the future. If you live in an area where the single-dose Johnson & Johnson vaccine is available, then you can be fully vaccinated after just one dose. You can read more here about the vaccine response in people who’ve had Covid-19.

Q: Will the vaccines work against the new variants that have emerged around the world?

The vaccines appear to be effective against a new variant that originated in Britain and is quickly becoming dominant in the United States. But some variants of the coronavirus, particularly one first identified in South Africa and one in Brazil, appear to be more adept at dodging antibodies in vaccinated people.

While that sounds worrisome, there’s reason to be hopeful. Vaccinated people exposed to a more resistant variant still appear to be protected against serious illness. And scientists have a clear enough understanding of the variants that they already are working on developing booster shots that will target the variants. The variants identified in South Africa and Brazil are not yet widespread in the United States.

People who are vaccinated should still wear masks in public and comply with public health guidelines, but you shouldn’t live in fear of variants, said Dr. Peter J. Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston. “If you’re vaccinated, you should feel pretty confident about how protected you are,” said Dr. Hotez. “It’s unlikely you’ll ever go to a hospital or an I.C.U. with Covid-19. In time you’re going to see a recommendation for a booster.”

I hope these answers will reassure you about your own vaccine experience. You can find a more complete list of questions and answers in our special vaccine tool “Answers to All Your Questions About Getting Vaccinated Against Covid-19.”

What to Expect When You Get Your Covid Vaccine

What to Expect When You Get Your Covid Vaccine

Kevin Mohatt for The New York Times

With more Americans becoming eligible for vaccination, many have questions about what the experience is like.

Here, Times science and health reporters answer some frequently asked questions about vaccination →

Mar. 10, 2021
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Can Vaccinated People Spread the Virus? We Don’t Know, Scientists Say.

Researchers pushed back after the C.D.C. director asserted that vaccinated people “do not carry the virus.”

The Centers for Disease Control and Prevention on Thursday walked back controversial comments made by its director, Dr. Rochelle P. Walensky, suggesting that people who are vaccinated against the coronavirus never become infected or transmit the virus to others.

The assertion called into question the precautions that the agency had urged vaccinated people to take just last month, like wearing masks and gathering only under limited circumstances with unvaccinated people.

“Dr. Walensky spoke broadly during this interview,” an agency spokesman told The Times. “It’s possible that some people who are fully vaccinated could get Covid-19. The evidence isn’t clear whether they can spread the virus to others. We are continuing to evaluate the evidence.”

The agency was responding in part to criticism from scientists who noted that current research was far from sufficient to claim that vaccinated people cannot spread the virus.

The data suggest that “it’s much harder for vaccinated people to get infected, but don’t think for one second that they cannot get infected,” said Paul Duprex, director of the Center for Vaccine Research at the University of Pittsburgh.

In a television interview with MSNBC’s Rachel Maddow, Dr. Walensky referred to data published by the C.D.C. showing that one dose of the Moderna or Pfizer-BioNTech vaccine was 80 percent effective at preventing infection, and two doses were 90 percent effective.

That certainly suggested that transmission from vaccinated people might be unlikely, but Dr. Walensky’s comments hinted that protection was complete. “Our data from the C.D.C. today suggests that vaccinated people do not carry the virus, don’t get sick,” she said. “And that it’s not just in the clinical trials, it’s also in real-world data.”

Dr. Walensky went on to emphasize the importance of continuing to wear masks and maintain precautions, even for vaccinated people. Still, the brief comment was widely interpreted as saying that the vaccines offered complete protection against infection or transmission.

In a pandemic that regularly spawns scientific misunderstanding, experts said they were sympathetic to Dr. Walensky and her obvious desire for Americans to continue to take precautions. It was only Monday that she said rising caseloads had left her with a sense of “impending doom.”

“If Dr. Walensky had said most vaccinated people do not carry virus, we would not be having this discussion,” said John Moore, a virologist at Weill Cornell Medicine in New York.

“What we know is the vaccines are very substantially effective against infection — there’s more and more data on that — but nothing is 100 percent,” he added. “It is an important public health message that needs to be gotten right.”

Misinterpretation could disrupt the agency’s urgent pleas for immunization, some experts said. As of Wednesday, 30 percent of Americans had received at least one dose of a vaccine and 17 percent were fully immunized.

“There cannot be any daylight between what the research shows — really impressive but incomplete protection — and how it is described,” said Dr. Peter Bach, director of the Center for Health Policy and Outcomes at Memorial Sloan Kettering Cancer Center in New York.

“This opens the door to the skeptics who think the government is sugarcoating the science,” Dr. Bach said, “and completely undermines any remaining argument why people should keep wearing masks after being vaccinated.”

All of the coronavirus vaccines are spectacularly successful at preventing serious disease and death from Covid-19, but how well they prevent infection has been less clear.

Clinical trials of the vaccines were designed only to assess whether the vaccines prevent serious illness and death. The research from the C.D.C. on Monday brought the welcome conclusion that the vaccines are also extremely effective at preventing infection.

The study enrolled 3,950 health care workers, emergency responders and others at high risk of infection. The participants swabbed their noses each week and sent the samples in for testing, which allowed federal researchers to track all infections, symptomatic or not. Two weeks after vaccination, the vast majority of vaccinated people remained virus-free, the study found.

Follow-up data from clinical trials support that finding. In results released by Pfizer and BioNTech on Wednesday, for example, 77 people who received the vaccine had a coronavirus infection, compared with 850 people who got a placebo.

“Clearly, some vaccinated people do get infected,” Dr. Duprex said. “We’re stopping symptoms, we’re keeping people out of hospitals. But we’re not making them completely resistant to an infection.”

The number of vaccinated people who become infected is likely to be higher among those receiving vaccines made by Johnson & Johnson and AstraZeneca, which have a lower efficacy, experts said. (Still, those vaccines are worth taking, because they uniformly prevent serious illness and death.)

Infection rates may also be higher among people exposed to a virus variant that can sidestep the immune system.

Cases across the country are once again on the upswing, threatening a new surge. Dr. Walensky’s comment came just a day after she made an emotional appeal to the American public to continue taking precautions.

“I am asking you to just hold on a little longer, to get vaccinated when you can, so that all of those people that we all love will still be here when this pandemic ends,” she said.

Given the rising numbers, it’s especially important that immunized people continue to protect those who have not yet been immunized against the virus, experts said.

“Vaccinated people should not be throwing away their masks at this point,” Dr. Moore said. “This pandemic is not over.”

The Pfizer-BioNTech Vaccine Is Said to Be Powerfully Protective in Adolescents

A clinical trial found no infections among vaccinated children ages 12 to 15, the companies said, and there were no serious side effects. The data have not yet been reviewed by independent experts.

The Pfizer-BioNTech coronavirus vaccine is extremely effective in adolescents 12 to 15 years old, perhaps even more so than in adults, the companies reported on Wednesday. No infections were found among children who received the vaccine in a recent clinical trial, the drug makers said; the children produced strong antibody responses and experienced no serious side effects.

The findings, if they hold up, may speed a return to normalcy for millions of American families. Depending on regulatory approval, vaccinations could begin before the start of the next academic year for middle school and high school students, and for elementary school children not long after.

The companies announced the results in a news release that did not include detailed data from the trial, which has not yet been peer-reviewed nor published in a scientific journal. Still, the news drew praise and excitement from experts.

“Oh my god, I’m so happy to see this — this is amazing,” said Akiko Iwasaki, an immunologist at Yale University. If the vaccines’s performance in adults was A-plus, the results in children were “A-plus-plus.”

The good news arrives even as the country records another rise in infections and health officials renew calls for Americans to heed precautions and get vaccinated. On Monday, Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, said that rising cases had left her with sense of “impending doom,” while President Biden called on state and local officials to reinstate mask mandates.

Vaccination efforts are accelerating throughout the nation. As of Tuesday, 29 percent of adults had received at least one dose of a coronavirus vaccine, and 16 percent had been fully inoculated, according to the C.D.C.

But the country cannot hope to reach herd immunity — the point at which immunity becomes so widespread that the coronavirus slows its crawl through the population — without also inoculating the youngest Americans, some experts say. Children under 18 account for about 23 percent of the population in the United States.

“The sooner that we can get vaccines into as many people as possible, regardless of their age, the sooner we will be able to really feel like we’re ending this pandemic for good,” said Angela Rasmussen, a virologist affiliated with Georgetown University in Washington.

Data from Israel suggest that vaccinating adults alone can significantly decrease the number of cases, but “long term, to hit the herd immunity threshold, we will have to vaccinate children,” she said.

The trial included 2,260 adolescents ages 12 to 15. The children received two doses of the vaccine three weeks apart — the same amounts and schedule used for adults — or a placebo of saltwater.

The researchers recorded 18 cases of coronavirus infection in the placebo group, and none among the children who received the vaccine. Still, the low number of infections makes it difficult to be too specific about the vaccine’s efficacy in the population at large, Dr. Rasmussen said.

“But obviously, it looks good for the vaccine if there were zero Covid cases among the vaccinated people,” she added.

The adolescents who got the vaccine produced much higher levels of antibodies on average, compared with participants 16 to 25 years of age in an earlier trial. The children experienced the same minor side effects as older participants, although the companies declined to be more specific.

Dr. Iwasaki said she had expected antibody levels in adolescents to be comparable to those in young adults. “But they’re getting even better levels from the vaccines,” she said. “That’s really incredible.”

She and other experts cautioned that the vaccine might be less effective in children, and adults, against some of the variants that have begun circulating in the United States.

Pfizer and BioNTech have begun a clinical trial of the vaccine in children under 12 and started inoculations of children ages 5 to 11 just last week. Company scientists plan to start testing the vaccine next week in even younger children, ages 2 to 5, followed by trials in children ages 6 months to 2 years.

Results from that three-phase trial are expected in the second half of the year, and the companies hope to make the vaccine available for children under 12 early next year.

“We share the urgency to expand the use of our vaccine to additional populations and are encouraged by the clinical trial data from adolescents between the ages of 12 and 15,” Albert Bourla, Pfizer’s chairman and chief executive officer, said in a statement.

Moderna has also been testing its vaccine in children. Results from a trial in adolescents ages 12 to 17 are expected in the next few weeks and in children 6 months to 12 years old in the second half of this year.

AstraZeneca started testing its vaccine in children 6 months and older last month, and Johnson & Johnson has said it will wait for results from trials in older children before testing its vaccine in children under 12.

Some parents have said they are reluctant to immunize their children because the risk posed by the virus is low. Children make up fewer than 1 percent of deaths from Covid-19, but about 2 percent of children who get the illness require hospital care.

The new results may not sway all of those parents, but they may reassure parents who have been wary of the vaccines, said Jennifer Nuzzo, an epidemiologist at the Johns Hopkins Center for Health Security.

“While I don’t think we have to wait until children are vaccinated to fully reopen schools, being able to vaccinate children may help some families feel safer about returning to school,” she said.

Pfizer and BioNTech plan to request from the Food and Drug Administration an amendment to the emergency use authorization for their vaccine, in hopes of beginning immunizations of older children before the start of the next school year. The companies also are planning to submit their data for peer review and publication in a scientific journal.

They will monitor the participants for two years after the second dose to assess the vaccine’s long-term safety and efficacy. Side effects of vaccines are usually apparent within the first six weeks, said Dr. Kristin Oliver, a pediatrician and vaccine expert at Mount Sinai Hospital in New York. “Still, it’s good to know that safety monitoring is going to continue,” she said.

The C.D.C. recommends that people avoid getting other vaccines for two weeks before and after receiving the two doses of the coronavirus vaccine.

But children receive more vaccines in the few weeks before the school year than at any other time, Dr. Oliver noted, so pediatricians and parents should aim to get those other immunizations done earlier than usual.

The coronavirus vaccines should ideally be given by pediatricians who have deep experience in immunizing children, Dr. Oliver added. “Now is the time to start planning how that rollout is going to take place in this age group,” she said.

Getting One Vaccine Is Good. How About Mix-and-Match?

Researchers are exploring the possible benefits of pairing doses from two different Covid-19 vaccines.

In January, Britain made a change to its vaccine guidelines that shocked many health experts: If the second dose of one vaccine wasn’t available, patients could be given a different one.

The new rule was based on sheer guesswork; there was no scientific data at the time demonstrating that mixing two coronavirus vaccines was safe and effective. But that may change soon.

In February, researchers at the University of Oxford began a trial in which volunteers received a dose of the Pfizer-BioNTech vaccine followed by a dose of AstraZeneca’s formulation, or vice versa. This month, the researchers will start analyzing the blood of the subjects to see how well the mix-and-match approach works.

As growing numbers of vaccines are being authorized, researchers are testing other combinations. A few are in clinical trials, while others are being tested in animals for now.

Mixing vaccines might do more than just help overcome supply bottlenecks. Some researchers suspect that a pair of different vaccines might work better than two doses of the same one.

“I think we’re on the cusp of some interesting data,” said Adam Wheatley, an immunologist at the University of Melbourne in Australia.

The concept of mixing vaccines — sometimes called a heterologous prime-boost — is not new to our pandemic era. For decades, researchers have investigated the approach, hoping to find potent combinations against a range of viruses, such as influenza, H.I.V. and Ebola.

But scientists had little to show for all that research. It was easy enough to demonstrate that two vaccines may work well together in a mouse. But running full-blown clinical trials on a combination of vaccines is a tall order.

“For a single company to develop two parallel arms of a vaccine is twice the work and twice the cost,” Dr. Wheatley said.

Some of the early successes for heterologous prime-boosts came in the search for vaccines for Ebola. Many researchers focused their efforts on presenting the immune system with a protein found on the surface of the Ebola virus.

The gene for that protein was inserted into a different, harmless virus. When people received an injection of the vaccine, the harmless virus entered their cells; the cells then read the instructions in the Ebola gene and mass-produced Ebola’s surface protein. The immune system encountered the Ebola protein and made antibodies against it. And those antibodies protected the vaccinated people if they became infected with a full-blown Ebola virus.

This type of vaccine, called a viral vector vaccine, came with a big risk: The recipients might develop immunity to the viral vector after just the first dose. When the second dose arrived, their immune systems could swiftly wipe out the viral vector before it delivered its payload.

A number of vaccine makers decided to sidestep this potential threat by using different viruses for each dose. That way, the viral vectors in the second dose would be as new to the immune system as the first was. In 2017, for example, researchers at the Gamaleya Research Institute in Russia created an Ebola vaccine whose first dose contained a virus called an adenovirus. The second shot used another virus, called vesicular stomatitis virus.

When the Covid-19 pandemic began last year, the Gamaleya researchers used a similar strategy to create vaccines against the new coronavirus. The first dose used the same adenovirus as in their Ebola vaccine, called Ad5. The second dose contained a different human adenovirus, Ad26. The researches inserted a gene into both viruses for the protein on the surface of the coronavirus, called spike.

Studies revealed that the vaccine, now known as Sputnik V, provided a strong defense against Covid-19. In clinical trials, the researchers found that it had an efficacy of 91.6 percent. Sputnik V is now in use in Russia and 56 other countries.

Recently, the Gamaleya institute joined forces with AstraZeneca, which makes its own Covid-19 vaccine. AstraZeneca’s consists of two doses of a chimpanzee adenovirus called ChAdOx1. Last week, the company reported that its vaccine had an efficacy of 76 percent.

The Gamaleya and AstraZeneca teams want to see how well their vaccines work together. They have registered a pair of clinical trials in which volunteers will receive a dose of AstraZeneca’s ChAdOx1 and another of Sputnik V’s Ad26.

A spokesman for AstraZeneca said that one trial in Azerbaijan is underway, and a second, in Russia, is still under review by the country’s ministry of health.

Dr. Jakob Cramer, the head of clinical development at CEPI, a vaccine development organization, said that vaccines using viral vectors were not the only kind that might benefit from mixing. In fact, certain combinations might provoke a different, more effective immune response than a single type of vaccine. “Immunologically, there are several arguments in favor of exploring heterologous priming,” Dr. Kramer said.

Another kind of Covid-19 vaccine being tested contains the actual spike protein, rather than genetic instructions for it. Some of the vaccines contain the entire protein; others contain just a fragment of it. Currently, there are 29 protein-based vaccines for Covid-19 in clinical trials, although none have been authorized yet.

Dr. Wheatley and his colleagues have been testing protein-based vaccines in mice. They injected the full spike protein into the animals as a first dose. For the second dose, they injected only the tip of the spike, a region known as the receptor-binding domain, or R.B.D.

Dr. Wheatley and his colleagues found that the mixture worked better than two doses of the spike or of the R.B.D.

The researchers suspect that the first dose produces a broad range of antibodies that can stick to spots along the length of the spike protein, and that the second dose delivers a big supply of particularly potent antibodies to the tip of the spike. Together, the assortment of antibodies does a better job of stopping the coronavirus.

“You’re able to basically take that initial immunity that was elicited to that spike vaccine, and then really focus it down onto that R.B.D.,” Dr. Wheatley said.

Other combinations of vaccines may bring benefits of their own. Some vaccines, especially protein-based ones, do a good job of generating antibodies. Others, such as viral vectors, are better at training immune cells. A viral vector followed by a protein boost might offer the best of both worlds.

John Moore, a virologist at Weill Cornell Medicine, cautioned that there was no guarantee that clinical trials would reveal a benefit to mixing vaccines. In the search for an H.I.V. vaccine, researchers tried combining viral vectors and protein boost without success, he noted. Still, Dr. Moore said, the story might turn out differently for coronavirus vaccines.

“I’d like to see these studies done,” he said. “Doing it in the Covid space is completely rational, but may not be necessary.”

Some researchers are investigating heterologous vaccines not to find a superior mixture, but simply to open up more options for countries desperate to vaccinate their populations. Last week, India held back exports of vaccines to other countries as it grappled with a surge of Covid-19. For countries that were counting on those vaccines, a safe alternative for second doses could save lives.

After Britain was criticized in January for suggesting that vaccines could be mixed, researchers at the University of Oxford set out to put the idea to a formal test. In a trial called Com-Cov, they recruited 830 volunteers to test the two vaccines authorized by the British government: AstraZeneca’s adenovirus-based vaccine and the vaccine by Pfizer-BioNTech.

Pfizer-BioNTech’s vaccine uses a fundamentally different technology to produce spike proteins in the body. It contains tiny bubbles with genetic molecules called RNA. Once the bubbles fuse to cells, the cells use the RNA to make spike proteins.

One group of volunteers is receiving a Pfizer-BioNTech shot followed by AstraZeneca, while another will receive them in the reverse order. The other volunteers are receiving the standard two-dose version of the vaccines.

Later this month, the Oxford team will draw blood from the volunteers, examining their antibodies and immune cells to see whether the heterologous prime-boost creates an immune response roughly as strong as two doses of each of the authorized vaccines.

If more vaccines are authorized in Britain, the Com-Cov team may add them to the trial. Dr. Matthew Snape, who is leading the Com-COV trial, hopes it will be useful not just to his own country but to others that will be trying to vaccinate their citizens over the next few years.

“It might be that actually this flexibility becomes essential in the future,” he said.

Dr. Cramer said CEPI is planning to support additional heterologous prime-boost studies. There are plenty of possible studies to run. Worldwide, 13 vaccines are now in use against Covid-19, with 67 more in clinical trials.

“In the current situation, we have a quite a luxurious position of having so many advanced, effective vaccines,” Dr. Wheatley said.

As the number of authorized vaccines grows, the possible combinations in which they can be used will explode. Recently, researchers at China’s National Institutes for Food and Drug Control scaled up their research on heterologous prime-boosts by trying out four different vaccines that have either been authorized in China or are in late-stage clinical trials there — vaccines based on adenoviruses, proteins, RNA and coronaviruses that have been inactivated with chemicals.

The researchers injected mice with a first dose of one vaccine, then a second dose of another. Some of the combinations caused the mice to produce stronger immune responses than mice that received the same vaccine for both doses.

Whether scientists carry out more experiments on other vaccines will depend on the willingness of the vaccine manufacturers. “You’re requiring quite large pharmaceutical companies to play nice together,” Dr. Wheatley said.

Dr. Bernard Moss, a virologist at the National Institute of Allergy and Infectious Diseases, suspects that a number of companies will be willing to let their vaccines be tested in combinations. “It’s always better to be a part of something that is going to be used,” he said, “than to wholly own something that isn’t.”

One Vaccine Is Good. How About Mixing Two?

Researchers are exploring the possible benefits of combining doses from two different Covid-19 vaccines.

In January, Britain made a change to its vaccine guidelines that shocked many health experts: If the second dose of one vaccine wasn’t available, patients could be given a different one.

The new rule was based on sheer guesswork; there was no scientific data at the time demonstrating that mixing two coronavirus vaccines was safe and effective. But that may change soon.

In February, researchers at the University of Oxford began a trial in which volunteers received a dose of the Pfizer-BioNTech vaccine followed by a dose of AstraZeneca’s formulation, or vice versa. This month, the researchers will start analyzing the blood of the subjects to see how well the mix-and-match approach works.

As a growing number of vaccines are being authorized, researchers are testing other combinations. A few are in clinical trials, while others are being tested in animals for now.

Mixing vaccines might do more than just help overcome supply bottlenecks. Some researchers suspect that a pair of different vaccines might work better than two doses of the same one.

“I think we’re on the cusp of some interesting data,” said Adam Wheatley, an immunologist at the University of Melbourne in Australia.

The concept of mixing vaccines — sometimes called a heterologous prime-boost — is not new to our pandemic era. For decades, researchers have investigated the approach, hoping to find potent combinations against a range of viruses, such as influenza, H.I.V. and Ebola.

But scientists had little to show for all that research. It was easy enough to demonstrate that two vaccines may work well together in a mouse. But running full-blown clinical trials on a combination of vaccines is a tall order.

“For a single company to develop two parallel arms of a vaccine is twice the work and twice the cost,” Dr. Wheatley said.

Some of the early successes for heterologous prime-boosts came in the search for vaccines for Ebola. Many researchers focused their efforts on presenting the immune system with a protein found on the surface of the Ebola virus.

The gene for that protein was inserted into a different, harmless virus. When people received an injection of the vaccine, the harmless virus entered their cells; the cells then read the instructions in the Ebola gene and mass-produced Ebola’s surface protein. The immune system encountered the Ebola protein and made antibodies against it. And those antibodies protected the vaccinated people if they became infected with a full-blown Ebola virus.

This type of vaccine, called a viral vector vaccine, came with a big risk: The recipients might develop immunity to the viral vector after just the first dose. When the second dose arrived, their immune systems could swiftly wipe out the viral vector before it delivered its payload.

A number of vaccine makers decided to sidestep this potential threat by using different viruses for each dose. That way, the viral vectors in the second dose would be as new to the immune system as the first was. In 2017, for example, researchers at the Gamaleya Research Institute in Russia created an Ebola vaccine whose first dose contained a virus called an adenovirus. The second shot used another virus, called vesicular stomatitis virus.

When the Covid-19 pandemic began last year, the Gamaleya researchers used a similar strategy to create vaccines against the new coronavirus. The first dose used the same adenovirus as in their Ebola vaccine, called Ad5. The second dose contained a different human adenovirus, Ad26. The researches inserted a gene into both viruses for the protein on the surface of the coronavirus, called spike.

Studies revealed that the vaccine, now known as Sputnik V, provided a strong defense against Covid-19. In clinical trials, the researchers found that it had an efficacy of 91.6 percent. Sputnik V is now in use in Russia and 56 other countries.

Recently, the Gamaleya institute joined forces with AstraZeneca, which makes its own Covid-19 vaccine. AstraZeneca’s consists of two doses of a chimpanzee adenovirus called ChAdOx1. Last week, the company reported that its vaccine had an efficacy of 76 percent.

The Gamaleya and AstraZeneca teams want to see how well their vaccines work together. They have registered a pair of clinical trials in which volunteers will receive a dose of AstraZeneca’s ChAdOx1 and another of Sputnik V’s Ad26.

A spokesman for AstraZeneca said that one trial in Azerbaijan is underway, and a second, in Russia, is still under review by the country’s ministry of health.

Dr. Jakob Cramer, the head of clinical development at CEPI, a vaccine development organization, said that vaccines using viral vectors were not the only kind that might benefit from mixing. In fact, certain combinations might provoke a different, more effective immune response than a single type of vaccine. “Immunologically, there are several arguments in favor of exploring heterologous priming,” Dr. Kramer said.

Another kind of Covid-19 vaccine being tested contains the actual spike protein, rather than genetic instructions for it. Some of the vaccines contain the entire protein; others contain just a fragment of it. Currently, there are 29 protein-based vaccines for Covid-19 in clinical trials, although none have been authorized yet.

Dr. Wheatley and his colleagues have been testing protein-based vaccines in mice. They injected the full spike protein into the animals as a first dose. For the second dose, they injected only the tip of the spike, a region known as the receptor-binding domain, or R.B.D.

Dr. Wheatley and his colleagues found that the mixture worked better than two doses of the spike or of the R.B.D.

The researchers suspect that the first dose produces a broad range of antibodies that can stick to spots along the length of the spike protein, and that the second dose delivers a big supply of particularly potent antibodies to the tip of the spike. Together, the assortment of antibodies does a better job of stopping the coronavirus.

“You’re able to basically take that initial immunity that was elicited to that spike vaccine, and then really focus it down onto that R.B.D.,” Dr. Wheatley said.

Other combinations of vaccines may bring benefits of their own. Some vaccines, especially protein-based ones, do a good job of generating antibodies. Others, such as viral vectors, are better at training immune cells. A viral vector followed by a protein boost might offer the best of both worlds.

John Moore, a virologist at Weill Cornell Medicine, cautioned that there was no guarantee that clinical trials would reveal a benefit to mixing vaccines. In the search for an H.I.V. vaccine, researchers tried combining viral vectors and protein boost without success, he noted. Still, Dr. Moore said, the story might turn out differently for coronavirus vaccines.

“I’d like to see these studies done,” he said. “Doing it in the Covid space is completely rational, but may not be necessary.”

Some researchers are investigating heterologous vaccines not to find a superior mixture, but simply to open up more options for countries desperate to vaccinate their populations. Last week, India held back exports of vaccines to other countries as it grappled with a surge of Covid-19. For countries that were counting on those vaccines, a safe alternative for second doses could save lives.

After Britain was criticized in January for suggesting that vaccines could be mixed, researchers at the University of Oxford set out to put the idea to a formal test. In a trial called Com-Cov, they recruited 830 volunteers to test the two vaccines authorized by the British government: AstraZeneca’s adenovirus-based vaccine and the vaccine by Pfizer-BioNTech.

Pfizer-BioNTech’s vaccine uses a fundamentally different technology to produce spike proteins in the body. It contains tiny bubbles with genetic molecules called RNA. Once the bubbles fuse to cells, the cells use the RNA to make spike proteins.

One group of volunteers is receiving a Pfizer-BioNTech shot followed by AstraZeneca, while another will receive them in the reverse order. The other volunteers are receiving the standard two-dose version of the vaccines.

Later this month, the Oxford team will draw blood from the volunteers, examining their antibodies and immune cells to see whether the heterologous prime-boost creates an immune response roughly as strong as two doses of each of the authorized vaccines.

If more vaccines are authorized in Britain, the Com-Cov team may add them to the trial. Dr. Matthew Snape, who is leading the Com-COV trial, hopes it will be useful not just to his own country but to others that will be trying to vaccinate their citizens over the next few years.

“It might be that actually this flexibility becomes essential in the future,” he said.

Dr. Cramer said CEPI is planning to support additional heterologous prime-boost studies. There are plenty of possible studies to run. Worldwide, 13 vaccines are now in use against Covid-19, with 67 more in clinical trials.

“In the current situation, we have a quite a luxurious position of having so many advanced, effective vaccines,” Dr. Wheatley said.

As the number of authorized vaccines grows, the possible combinations in which they can be used will explode. Recently, researchers at China’s National Institutes for Food and Drug Control scaled up their research on heterologous prime-boosts by trying out four different vaccines that have either been authorized in China or are in late-stage clinical trials there — vaccines based on adenoviruses, proteins, RNA and coronaviruses that have been inactivated with chemicals.

The researchers injected mice with a first dose of one vaccine, then a second dose of another. Some of the combinations caused the mice to produce stronger immune responses than mice that received the same vaccine for both doses.

Whether scientists carry out more experiments on other vaccines will depend on the willingness of the vaccine manufacturers. “You’re requiring quite large pharmaceutical companies to play nice together,” Dr. Wheatley said.

Dr. Bernard Moss, a virologist at the National Institute of Allergy and Infectious Diseases, suspects that a number of companies will be willing to let their vaccines be tested in combinations. “It’s always better to be a part of something that is going to be used,” he said, “than to wholly own something that isn’t.”

Family Travel Gets Complicated Without a Covid Vaccine for Kids

Amid the chatter of travel’s long-awaited rebound one year into the pandemic, many families with children feel largely left out of the conversation.

Nearly every summer, Ada Ayala, a teacher, and her husband, Oscar Cesar Pleguezeulos, travel with their children to visit Mr. Cesar Pleguezeulos’s parents in Spain. But this year, even though they will both soon be fully vaccinated in their home state of Florida, they are changing their plans. The reason? There is still no pediatric Covid-19 vaccine available for their kids.

The travel industry, buoyed by news of vaccine rollouts, is anticipating a summer rush after a year of devastation. But amid the chatter of travel’s long-awaited rebound, many families with children — who comprise roughly 30 percent of the global travel market — say they are largely being left out of the conversation.

In a March survey on Bébé Voyage, an online community for traveling families, 90 percent of respondents said that amid unclear guidelines on Covid-19 testing, they were searching for flexible bookings. The topic also comes up often on Bébé Voyage’s Facebook page, particularly among parents in the United States. “It’s the Americans in the group that are the most nervous traveling with kids,” said the Bébé Voyage chief executive, Marianne Perez de Fransius.

Ms. Ayala, 44, is among those nervous parents. “If it wasn’t for the kids, we would definitely be flying this summer,” she said. Ms. Ayala already received her shot as a teacher. Her husband, also 44, will soon receive his shots, too, because Florida recently opened vaccinations to those age 40 and up. But their children, Charlise, 6, and Oscar, 2, will have to wait many more months to be inoculated.

“My 2-year-old isn’t going to wear a mask for 10 hours on a flight, and I don’t know if I want to expose him for a 16-hour trip with layovers,” Ms. Ayala said. “I’ll feel more confident when vaccination reaches more people worldwide, or at least in the destinations we want to go.”

Nearly one in three adults in the United States have now received at least one dose of the Covid-19 vaccine. But a full pediatric Covid-19 vaccine currently isn’t expected until the end of 2021 at the earliest, and while they wait, parents are struggling to figure out how they, too, can travel safely this summer, and even where their children are welcome as rules on quarantine and testing continue to shift.

“This is the elephant in the room right now,” said Cate Caruso, an adviser for Virtuoso, a network of luxury travel agencies, who also owns her own travel planning company, True Places Travel. The potential that a child could become infected with Covid-19 while abroad and not be allowed on a return flight, she said, is a major deterrent for parents. “Anywhere you go outside of the U.S. right now, you’ve got to think about how you’re going to get back in,” she said. “It’s leaving behind a whole bunch of people who are ready to go.”

In Ms. Ayala’s case, a compromise has been struck: If and when Spain — which is currently closed to American travelers — opens its borders, Mr. Cesar will travel to Spain with their daughter, Charlise, while Ms. Ayala will remain in Florida with Oscar. “She goes to school and is very good with wearing her mask, cleaning her hands and keeping distance,” Ms. Ayala said of her daughter. “So I think she can be safe. But it’s just not possible with a baby.”

But she doesn’t plan to stay home all summer. Whether or not her husband and daughter make it to Spain, Ms. Ayala is planning a family road trip at some point this summer, likely within Florida.

After a year of road trips, R.V.s and rental cottages, many Americans are now ready to fly again: Online searches for late-summer flights are up as much as 75 percent, and hotels on both coasts are reporting that they are sold out through October. But families, more than any other travel sector, continue to play it safe.

Family travel plans for this summer are more low-key than two years ago, with bookings to Mount Rushmore National Memorial, in the Black Hills of South Dakota, reported to be significantly up.
Family travel plans for this summer are more low-key than two years ago, with bookings to Mount Rushmore National Memorial, in the Black Hills of South Dakota, reported to be significantly up.Tannen Maury/EPA, via Shutterstock

Rovia, a membership-based global travel agency that works with both travelers and travel agents, reports that beach and camping destinations within driving distance are the most popular choices for families this summer. An exception? Disney World, which is seeing an uptick in reservations for summer from families looking to visit while capacity remains limited (and lines, as a result, remain shorter).

“The rate of couples traveling by air has increased faster, whereas families are still leaning toward travel by car and R.V. rentals,” said Jeff Gwynn, Rovia’s director of communications.

Montoya and Phil Hudson, who showcase their travels as a Black family on their popular blog, The Spring Break Family, are among them. “Most years we go pretty far — Spain, Italy, France, as far as we can go. This year it was about what’s reachable by car,” Ms. Hudson said. She and Mr. Hudson, who both work in the health care industry, are vaccinated, but admit they probably won’t be willing to fly with their two daughters, Leilah, 11, and Layla, 8, for several more months.

That’s because they want to wait for herd immunity to help keep their daughters safe. “The goal is to wait until the majority of the population is vaccinated, or has at least had the opportunity to become vaccinated,” Ms. Hudson said.

In addition to preferring driving over flying this summer, travel analysts say families with children will also continue to opt for rental homes over hotel rooms.

In fact, when it comes to the vacation cottage market, parents are booking faster than anyone else. “Families are the number one group expected to travel in 2021,” said Vered Schwarz, the president and chief operating officer of Guesty, a short-term property management platform which reports that its summer reservations are already 110 percent higher than 2020, with families comprising more than 30 percent of those booking. “For families with unvaccinated children, private rentals are appealing — they are comfortable and they avoid hotels chock-full of crowded common areas,” she said.

The question of how to treat unvaccinated children who may be traveling with their parents is also presenting a legal and ethical minefield for American travel operators.

The European Union is considering a vaccine passport that will allow free travel within the bloc for those who can show proof of inoculation. In Israel, a green pass has been established for those who have been vaccinated, granting holders not just the ability to cross a border but also check into a hotel or eat inside a restaurant, but children are not exempt — so parents with unvaccinated children must dine outside at restaurants and find babysitters before heading to the gym or a show.

But in the United States, such policies are unlikely to take hold, said Chuck Abbott, the general manager of the InterContinental San Diego. “Most hotels would not ask for that information, because it violates the privacy of the guest,” he said. “Even putting vaccinated guests on a different floor than other guests would likely present a legal issue.”

Compared with summer 2019, families’ plans for summer 2021 are more low-key: Travelocity reports that bookings to Mount Rushmore and Nashville are significantly up over two years ago; internationally, family bookings to London, Paris and Rome, destinations that were top family sites in 2019, but have still not reopened to U.S. travel, are way down, while Cancún, which is currently open to American travelers without quarantine requirements, is up nearly 50 percent.

Some European countries, like Iceland, have begun inching open their borders, but only to passengers who are vaccinated. That means individuals who can present proof of the Covid-19 jab can bypass quarantine when they arrive — unless they are parents traveling with children.

“Unvaccinated children would still need to quarantine for five days, and the parents, of course, must stay with the child,” said Eric Newman, who owns the travel blog Iceland With Kids. “Iceland’s brand-new travel regulations are not friendly to families hoping to visit with children.”

After a year of virtual schooling and working from home, parents have no desire to quarantine with their kids, said Anthony Berklich, the founder of the travel platform Inspired Citizen. “What these destinations are basically saying is you can come but your children can’t,” he said.

Instead, families are opting for warm-weather destinations closer to home.

When the Centers for Disease Control and Prevention announced in January that proof of a negative PCR test would be required of all air passengers arriving in the United States, many tropical resorts — including more than a dozen Hyatt properties — began offering not just free on-site testing, but a deeply discounted room in which to quarantine in case that test comes back positive. That move, said Rebecca Alesia, a travel consultant with SmartFlyer, has been a boon for family travel business.

“What happens if the morning you’re supposed to come home, you get up and Junior has a surprise positive test?” she said. “A lot of my clients have booked this summer because of this policy.”

For parents struggling to decide how and when to return to travel, there is good news on the horizon, said Dr. Shruti Gohil, the medical director of infection prevention at the University of California, Irvine.

“The chances of a good pediatric vaccine coming soon are high,” she said, noting that both Pfizer and Moderna are already running pediatric trials on their vaccines. “There is no reason to think that the vaccine will have any untoward effects on children that we haven’t already noted in adults.”

In the meantime, she said, parents with children need to continue to be cautious. That doesn’t mean families shouldn’t travel at all, but she recommends choosing to drive rather than fly; to not allow unvaccinated children to play unmasked with children from other households; and to remain vigilant about wearing masks and regularly washing hands while on the road.

“We can’t keep saying that you can’t go anywhere,” she said. “At some point we have to have some kind of nuance around this. But this is a game we are all still playing until the virus is gone.”

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A Nursing Home’s Mission to Vaccinate Its Hesitant Staff

Almost all of the residents at Forest Hills of D.C. got their initial Covid-19 shots in January. But nearly half of the staff there had declined. Would an effort to change their minds succeed?

WASHINGTON — The Covid-19 vaccine had finally come to Forest Hills of D.C., a nursing home in a prosperous neighborhood of the nation’s capital, but there was a problem. Though nearly all of the home’s residents agreed to get the shots, nearly half its 200 staff members declined.

Tina Sandri, the chief executive, vowed not to let those numbers stand.

Over the next two months, rounding out the most bruising year of her long career in elder care, Ms. Sandri tried everything. She bombarded employees with text messages containing facts about the science behind the vaccines. She assigned a popular young worker to try to sway reluctant colleagues as an “influencer.” She set up a giant screen to show a television special that the Black actor and director Tyler Perry made to fight vaccine hesitancy — on a continuous loop, no less. Most of all, she worked to understand their concerns.

“You really have to listen to each person’s story and address it from that standpoint, so they feel, ‘This is a workplace that cares about me,’” she said.

Three months after the nation’s health care workers were among the first Americans to be eligible for the lifesaving new vaccines, long-term care facilities across the country continue to face a similar daunting challenge. The federal program that sent vaccinators from Walgreens and CVS into tens of thousands of nursing homes and assisted living residences has by one measure been strikingly successful, inoculating nearly all of the vulnerable residents of the facilities. Deaths in nursing homes have plummeted since the program began in late December.

But reaching the mostly low-wage employees of the facilities has proved far more difficult. A poll by The Washington Post and Kaiser Family Foundation conducted from Feb. 11 to March 7 found that half of the workers at nursing homes had yet to get even a first shot, and only 15 percent of that group said they definitely planned to.

At Forest Hills, the workers who turned down the vaccine during the center’s first vaccination event in early January included nurses, certified nursing assistants, members of the kitchen and activities staffs, and a security officer. Most were Black, reflecting the overall makeup of the home’s work force; many were immigrants from African countries, such as Nigeria, Liberia and Cameroon.

Ms. Sandri’s goal was to persuade — not pressure — them. But she found there was not one unifying story behind their refusal, and no straightforward message that helped to convince them.

She ruled out some tactics deployed by other nursing homes, including offering gift cards, bonuses or extra vacation days to employees who agreed to get the vaccine; Ms. Sandri considered those incentives inappropriate and called them “bribes.”

“We’re doing this because we care,” she said. “To dilute that message with other things is almost patronizing to people’s intellect.”

The vaccinators from Walgreens would come back twice more — in early February and early March — and Ms. Sandri had dozens of minds to change. By her count, there were still 92 employees who needed the shot.

Tina Sandri, right, chief executive of Forest Hills of D.C., receiving her vaccine shot. She wanted the first day of vaccinations to feel like a party, she said.
Tina Sandri, right, chief executive of Forest Hills of D.C., receiving her vaccine shot. She wanted the first day of vaccinations to feel like a party, she said.
Mariah Proctor, a security guard at Forest Hills, said her mother had said to her about the vaccine: “You don’t know the ingredients. You know nothing.”

January

Ms. Sandri, 57, a yoga and outdoors enthusiast whose manner is at once bustling and soothing, had arrived at Forest Hills only in May, replacing a predecessor who left after the coronavirus had taken hold.

Three residents at Forest Hills had died from the virus and 17 others had become ill, along with 45 members of the staff — a less devastating toll than at many other nursing homes, but still an ordeal. Another resident would die in February, after a flurry of cases over the holiday period.

For the first vaccination event, on Jan. 4, Ms. Sandri laid out snacks, took lots of pictures and played upbeat music — “the cookout kind!” — aiming to create a partylike atmosphere that could help people feel the hope and promise of getting immunized.

When Mariah Proctor, a security guard, arrived for her shift that day, she encountered the festive buzz — and the persistent question between colleagues: “Are you getting it?”

Her answer was no. A conversation with her mother, who she said had never taken her for vaccinations for fear of putting anything besides healthy food in her children’s bodies, had cemented her decision.

Ms. Proctor, 24, said her mother had told her: “You don’t even know what that is. You don’t know the ingredients. You know nothing.”

After the disappointing vaccination turnout that first day, and with morale dipping and emotions fragile as the pandemic wore on, Ms. Sandri changed her approach. She had been holding “huddles” with different departments to explain the science of the vaccines, but now, instead of continuing to load people with facts, she focused on asking them: What information do you need? What is your concern?

Miles Lee has been serving as an influencer of sorts at Forest Hills, talking to his co-workers about their feelings or offering to look up information for them about the vaccine.
Ms. Sandri reviewing the “Heroes of Hope” wall depicting staff members who have been vaccinated.

February

Ms. Proctor was taking a break from her shift with Deborah Childs, a colleague from the payroll department who had also refused the vaccine, when the vaccinators from Walgreens came back on a snowy day in early February.

This time, Ms. Childs agreed to get the vaccine.

“I looked up the company and, you know, I found out that they’ve been doing research on mRNA for over 10 years, so that made me feel a little bit better,” she said, referring to the molecule that is the active ingredient in the Moderna vaccine that Walgreens is offering.

She was still a little scared, especially after reading about a doctor in Miami who had developed a rare blood disorder days after getting the Pfizer shot and died two weeks later. Still, she said: “I’m ready to get back to my life. And I know that this is probably one of the ways that we’re going to get back to being normal.”

Ms. Proctor was wavering. “My emotions are everywhere,” she said. She had been watching co-workers who had received their shots and asking them how they felt. “I would say that I am educating myself a little more now, versus just saying, ‘I don’t want to do it,’” she said.

Yet, she ended up refusing the shot again that day.

She wasn’t afraid of needles — she had multiple tattoos, she said, laughing. So what was holding her back?

“Having a bad reaction, or not being able to adjust to it at all,” she said.

She had also heard some frightening things — even though she suspected they weren’t true. “I heard someone say the first couple of people who took it for the trial died,” she said. “I’m not going to believe those things, but you do keep them in the back of your head and it makes you scared.”

Still, Ms. Sandri’s efforts seemed to be paying off. Forty-eight more workers decided to get their first shot that day.

For those who remained unvaccinated, Ms. Sandri had four weeks to change their minds.

March

Janice Johnson, director of nursing and infection prevention at Forest Hills, checking on staff members on vaccination day.
Staff members waiting their turn for the shot.

Across the country, vaccine hesitancy was receding — a Pew poll conducted in late February found that 30 percent of Americans said they would probably or definitely not get vaccinated, down from the 39 percent who said the same in November. The poll also found that far more Black Americans were willing to get the vaccine than they were before, but Ms. Sandri did not find that to be true among the African immigrants on her staff.

For them, the half-hour Tyler Perry video that had been playing on repeat on a giant screen in the multipurpose room did not seemed to resonate.

Ms. Sandri, who is of Chinese descent, began to understand. “I’m Asian, but I’m not Japanese or Thai or Indian, and they are very different people,” she said. “Until we understand cultural sensitivities beyond the major skin color groups, we’re not going to be successful at reaching herd immunity levels with some of those subsets.”

She started planning to have her director of maintenance, an African immigrant who has been vaccinated, to talk to reluctant peers about his experience and their concerns, and to find leaders of local African churches who might be willing to do the same.

She also doubled down on what she believed was working best: listening to and addressing the concerns of her employees one by one — what she called a “time-intensive, conversation-intensive, case-by-case uphill climb.”

The key, she said, was to tailor her message to what would resonate most with each person.

“For analytical people, we provided data on number of cases, number of people in trials, percent of people who experience an immune response,” she said. “For relationship-based thinkers, we asked if they had any vulnerable friends or family members, and how having or not having the vaccine might impact the relationship.”

Still, as the date of the third vaccination event approached in early March, Ms. Proctor was tired — of the pandemic and the long loss of freedoms, but also of hearing every day at work about the importance of getting the shot. Ms. Sandri, whose office was just around the corner, stopped by frequently to chat and gently raise the benefits of being vaccinated.

“It feels a little — almost like peer pressure,” Ms. Proctor said.

At times, she envied people who worked outside health care, suspecting they were not being barraged with information about the vaccine in quite the same way. Yet, she had come to appreciate that the vaccine was a commodity that most people her age — and most people in general — did not have access to yet. Getting vaccinated, she told herself, could help protect her sister who lived with her. It would also protect her when she returned to her second job — bartending — and made long-delayed trips to Puerto Rico and Jamaica later in the year.

By March 8, the day of the final event at Forest Hills, she was close to talking herself into rolling up her sleeve. At Ms. Sandri’s urging, she had watched the Tyler Perry special and an online town-hall-style forum for workers at nursing homes about the vaccine, organized by the Black Coalition Against Covid-19.

“It gave me a little more confidence,” she said. “I don’t know anyone in my immediate circle that took the vaccine yet, and it just makes me feel like if no one else has done it, then maybe I should.”

Despite working to convince herself of the vaccine’s benefits over recent days, Ms. Procter grew concerned as she was about to get vaccinated. Ms. Sandri was there to reassure Ms. Proctor before her shot.
Ms. Childs, who was at first hesitant about getting the vaccine, received her second dose this month. “I’m ready to get back to my life,” she said. “And I know that this is probably one of the ways that we’re going to get back to being normal.”

The final tally

Fifteen minutes before her shift ended, Ms. Proctor made her way to the home’s all-purpose room — normally the sight of bingo games and movie nights — and took off her jacket. Scanning the consent form with its daunting questions — Have you ever had a severe allergic reaction to something? Do you have a bleeding disorder or weakened immune system? — made her feel “leery,” she said.

Still, she got the shot. As she lingered in an easy chair afterward, Ms. Sandri fluttered in to check on her, gently touching her bare arm.

“I don’t have any thoughts, really, besides wondering how I’m going to feel — that’s my main concern,” Ms. Proctor said. By the end of the day, 18 more co-workers, along with Ms. Proctor, had joined the ranks of the partly or fully vaccinated. They now make up 79 percent of the staff at Forest Hills.

“I’m ready to do cartwheels down the hallway,” Ms. Sandri said, noting that Forest Hills had surpassed the goal set by the American Health Care Association, a trade group, to vaccinate 75 percent of the nation’s nursing home work force by the end of June.

With the federal program ending soon, the city’s health department had agreed to provide doses for anyone in nursing homes who still needed them.

“Everyone’s fears are real, whether or not they are grounded in science or in something they believe right now,” Ms. Sandri said, recounting what she had learned from her staff over the past few months. “Beliefs change with time or new knowledge, so we have to ride it out. Listen hard, don’t judge and let them move at their own pace.”

Kenny Holston contributed reporting.

Getting to Yes: A Nursing Home’s Mission to Vaccinate Its Hesitant Staff

Almost all of the residents at Forest Hills of D.C. got their initial Covid-19 shots in January. But nearly half of the staff there had declined. Would an effort to change their minds succeed?

WASHINGTON — The Covid-19 vaccine had finally come to Forest Hills of D.C., a nursing home in a prosperous neighborhood of the nation’s capital, but there was a problem. Though nearly all of the home’s residents agreed to get the shots, nearly half its 200 staff members declined.

Tina Sandri, the chief executive, vowed not to let those numbers stand.

Over the next two months, rounding out the most bruising year of her long career in elder care, Ms. Sandri tried everything. She bombarded employees with text messages containing facts about the science behind the vaccines. She assigned a popular young worker to try to sway reluctant colleagues as an “influencer.” She set up a giant screen to show a television special that the Black actor and director Tyler Perry made to fight vaccine hesitancy — on a continuous loop, no less. Most of all, she worked to understand their concerns.

“You really have to listen to each person’s story and address it from that standpoint, so they feel, ‘This is a workplace that cares about me,’” she said.

Three months after the nation’s health care workers were among the first Americans to be eligible for the lifesaving new vaccines, long-term care facilities across the country continue to face a similar daunting challenge. The federal program that sent vaccinators from Walgreens and CVS into tens of thousands of nursing homes and assisted living residences has by one measure been strikingly successful, inoculating nearly all of the vulnerable residents of the facilities. Deaths in nursing homes have plummeted since the program began in late December.

But reaching the mostly low-wage employees of the facilities has proved far more difficult. A poll by The Washington Post and Kaiser Family Foundation conducted from Feb. 11 to March 7 found that half of the workers at nursing homes had yet to get even a first shot, and only 15 percent of that group said they definitely planned to.

At Forest Hills, the workers who turned down the vaccine during the center’s first vaccination event in early January included nurses, certified nursing assistants, members of the kitchen and activities staffs, and a security officer. Most were Black, reflecting the overall makeup of the home’s work force; many were immigrants from African countries, such as Nigeria, Liberia and Cameroon.

Ms. Sandri’s goal was to persuade — not pressure — them. But she found there was not one unifying story behind their refusal, and no straightforward message that helped to convince them.

She ruled out some tactics deployed by other nursing homes, including offering gift cards, bonuses or extra vacation days to employees who agreed to get the vaccine; Ms. Sandri considered those incentives inappropriate and called them “bribes.”

“We’re doing this because we care,” she said. “To dilute that message with other things is almost patronizing to people’s intellect.”

The vaccinators from Walgreens would come back twice more — in early February and early March — and Ms. Sandri had dozens of minds to change. By her count, there were still 92 employees who needed the shot.

Tina Sandri, right, chief executive of Forest Hills of D.C., receiving her vaccine shot. She wanted the first day of vaccinations to feel like a party, she said.
Tina Sandri, right, chief executive of Forest Hills of D.C., receiving her vaccine shot. She wanted the first day of vaccinations to feel like a party, she said.
Mariah Proctor, a security guard at Forest Hills, said her mother had said to her about the vaccine: “You don’t know the ingredients. You know nothing.”

January

Ms. Sandri, 57, a yoga and outdoors enthusiast whose manner is at once bustling and soothing, had arrived at Forest Hills only in May, replacing a predecessor who left after the coronavirus had taken hold.

Three residents at Forest Hills had died from the virus and 17 others had become ill, along with 45 members of the staff — a less devastating toll than at many other nursing homes, but still an ordeal. Another resident would die in February, after a flurry of cases over the holiday period.

For the first vaccination event, on Jan. 4, Ms. Sandri laid out snacks, took lots of pictures and played upbeat music — “the cookout kind!” — aiming to create a partylike atmosphere that could help people feel the hope and promise of getting immunized.

When Mariah Proctor, a security guard, arrived for her shift that day, she encountered the festive buzz — and the persistent question between colleagues: “Are you getting it?”

Her answer was no. A conversation with her mother, who she said had never taken her for vaccinations for fear of putting anything besides healthy food in her children’s bodies, had cemented her decision.

Ms. Proctor, 24, said her mother had told her: “You don’t even know what that is. You don’t know the ingredients. You know nothing.”

After the disappointing vaccination turnout that first day, and with morale dipping and emotions fragile as the pandemic wore on, Ms. Sandri changed her approach. She had been holding “huddles” with different departments to explain the science of the vaccines, but now, instead of continuing to load people with facts, she focused on asking them: What information do you need? What is your concern?

Miles Lee has been serving as an influencer of sorts at Forest Hills, talking to his co-workers about their feelings or offering to look up information for them about the vaccine.
Ms. Sandri reviewing the “Heroes of Hope” wall depicting staff members who have been vaccinated.

February

Ms. Proctor was taking a break from her shift with Deborah Childs, a colleague from the payroll department who had also refused the vaccine, when the vaccinators from Walgreens came back on a snowy day in early February.

This time, Ms. Childs agreed to get the vaccine.

“I looked up the company and, you know, I found out that they’ve been doing research on mRNA for over 10 years, so that made me feel a little bit better,” she said, referring to the molecule that is the active ingredient in the Moderna vaccine that Walgreens is offering.

She was still a little scared, especially after reading about a doctor in Miami who had developed a rare blood disorder days after getting the Pfizer shot and died two weeks later. Still, she said: “I’m ready to get back to my life. And I know that this is probably one of the ways that we’re going to get back to being normal.”

Ms. Proctor was wavering. “My emotions are everywhere,” she said. She had been watching co-workers who had received their shots and asking them how they felt. “I would say that I am educating myself a little more now, versus just saying, ‘I don’t want to do it,’” she said.

Yet, she ended up refusing the shot again that day.

She wasn’t afraid of needles — she had multiple tattoos, she said, laughing. So what was holding her back?

“Having a bad reaction, or not being able to adjust to it at all,” she said.

She had also heard some frightening things — even though she suspected they weren’t true. “I heard someone say the first couple of people who took it for the trial died,” she said. “I’m not going to believe those things, but you do keep them in the back of your head and it makes you scared.”

Still, Ms. Sandri’s efforts seemed to be paying off. Forty-eight more workers decided to get their first shot that day.

For those who remained unvaccinated, Ms. Sandri had four weeks to change their minds.

March

Janice Johnson, director of nursing and infection prevention at Forest Hills, checking on staff members on vaccination day.
Staff members waiting their turn for the shot.

Across the country, vaccine hesitancy was receding — a Pew poll conducted in late February found that 30 percent of Americans said they would probably or definitely not get vaccinated, down from the 39 percent who said the same in November. The poll also found that far more Black Americans were willing to get the vaccine than they were before, but Ms. Sandri did not find that to be true among the African immigrants on her staff.

For them, the half-hour Tyler Perry video that had been playing on repeat on a giant screen in the multipurpose room did not seemed to resonate.

Ms. Sandri, who is of Chinese descent, began to understand. “I’m Asian, but I’m not Japanese or Thai or Indian, and they are very different people,” she said. “Until we understand cultural sensitivities beyond the major skin color groups, we’re not going to be successful at reaching herd immunity levels with some of those subsets.”

She started planning to have her director of maintenance, an African immigrant whohas been vaccinated, to talk to reluctant peers about his experience and their concerns, and to find leaders of local African churches who might be willing to do the same.

She also doubled down on what she believed was working best: listening to and addressing the concerns of her employees one by one — what she called a “time-intensive, conversation-intensive, case-by-case uphill climb.”

The key, she said, was to tailor her message to what would resonate most with each person.

“For analytical people, we provided data on number of cases, number of people in trials, percent of people who experience an immune response,” she said. “For relationship-based thinkers, we asked if they had any vulnerable friends or family members, and how having or not having the vaccine might impact the relationship.”

Still, as the date of the third vaccination event approached in early March, Ms. Proctor was tired — of the pandemic and the long loss of freedoms, but also of hearing every day at work about the importance of getting the shot. Ms. Sandri, whose office was just around the corner, stopped by frequently to chat and gently raise the benefits of being vaccinated.

“It feels a little — almost like peer pressure,” Ms. Proctor said.

At times, she envied people who worked outside health care, suspecting they were not being barraged with information about the vaccine in quite the same way. Yet, she had come to appreciate that the vaccine was a commodity that most people her age — and most people in general — did not have access to yet. Getting vaccinated, she told herself, could help protect her sister who lived with her. It would also protect her when she returned to her second job — bartending — and made long-delayed trips to Puerto Rico and Jamaica later in the year.

By March 8, the day of the final event at Forest Hills, she was close to talking herself into rolling up her sleeve. At Ms. Sandri’s urging, she had watched the Tyler Perry special and an online town-hall-style forum for workers at nursing homes about the vaccine, organized by the Black Coalition Against Covid-19.

“It gave me a little more confidence,” she said. “I don’t know anyone in my immediate circle that took the vaccine yet, and it just makes me feel like if no one else has done it, then maybe I should.”

Despite working to convince herself of the vaccine’s benefits over recent days, Ms. Procter grew concerned as she was about to get vaccinated. Ms. Sandri was there to reassure Ms. Proctor before her shot.
Ms. Childs, who was at first hesitant about getting the vaccine, received her second dose this month. “I’m ready to get back to my life,” she said. “And I know that this is probably one of the ways that we’re going to get back to being normal.”

The final tally

Fifteen minutes before her shift ended, Ms. Proctor made her way to the home’s all-purpose room — normally the sight of bingo games and movie nights — and took off her jacket. Scanning the consent form with its daunting questions — Have you ever had a severe allergic reaction to something? Do you have a bleeding disorder or weakened immune system? — made her feel “leery,” she said.

Still, she got the shot. As she lingered in an easy chair afterward, Ms. Sandri fluttered in to check on her, gently touching her bare arm.

“I don’t have any thoughts, really, besides wondering how I’m going to feel — that’s my main concern,” Ms. Proctor said. By the end of the day, 18 more co-workers, along with Ms. Proctor, had joined the ranks of the partly or fully vaccinated. They now make up 79 percent of the staff at Forest Hills.

“I’m ready to do cartwheels down the hallway,” Ms. Sandri said, noting that Forest Hills had surpassed the goal set by the American Health Care Association, a trade group, to vaccinate 75 percent of the nation’s nursing home work force by the end of June.

With the federal program ending soon, the city’s health department had agreed to provide doses for anyone in nursing homes who still needed them.

“Everyone’s fears are real, whether or not they are grounded in science or in something they believe right now,” Ms. Sandri said, recounting what she had learned from her staff over the past few months. “Beliefs change with time or new knowledge, so we have to ride it out. Listen hard, don’t judge and let them move at their own pace.”

Kenny Holston contributed reporting.

When Can Vaccinated People Date Again?

A slew of new ads show sloppy kisses. Air travel is ticking back up. And impending vaccination can seem like a ticket back to normalcy for 20-somethings in the United States, many of whom feel desperate to get back to their 2019 social lives. Cramped parties. Strobe-lit dance floors. The ability to spontaneously text a friend: Want to grab a drink?

Younger adults have played a disproportionate role in spreading the coronavirus. A report from the Centers for Disease Control and Prevention showed that from June to August 2020, Covid infections among 20- to 29-year-olds surged, accounting for more than 20 percent of the country’s total cases. Shortly after, data showed that those cases then led to an increase in infections among middle-aged and older people, potentially contributing to a national surge in cases.

Now, as older adults have been prioritized for vaccination and about two-thirds of those over 65 have received at least one dose, their risk of getting severely ill after catching the virus from an infected young person has decreased significantly.

But that doesn’t mean it’s completely safe to party like it’s 2019.

How you calculate your risk of passing the virus onto more vulnerable people will hinge on your individual circumstances: whether you live with parents or people in their 20s, whether there are people at risk for severe outcomes of Covid in your social circle. “There’s not a simple red light, green light,” said Dr. William Schaffner, an infectious disease expert at Vanderbilt University.

Here are some answers to common questions about what, in general, younger adults who are low risk can do when they’re fully vaccinated.

Can we just go back to normal?

A return to a kind of normal is coming, experts stressed, but there are still many unknowns about how the next few months will play out. While rising vaccination rates and falling cases are encouraging, said Dr. Schaffner, there are three situations that could hamper or negate that progress: if people refuse vaccination, if community transmission rates stay high and if virus variants render vaccines less effective.

“If the older and younger adults get vaccines, and the variants are not too variant, then we could have lots of pool parties,” he said. “Bars could open up.”

“The movement back to normal life should be a slow step-by-step,” said Tara Kirk Sell, a senior associate at the Johns Hopkins Center for Health Security, who researches large-scale health events. She recommended that people pick out one riskier activity they’ve been craving during the pandemic — seeing friends, going out to eat — and do that to celebrate their vaccination. “Then it should be a gradual move forward, rather than this huge explosion of, ‘I’m free!’,” she said.

Lelanie Foster for The New York Times
Lelanie Foster for The New York Times

But much of that is dependent on how much virus is circulating in your community.

“Once you get to a combination of hardly any cases in the community and a high proportion of people vaccinated — then, everything changes,” said Dr. Paul E. Sax, an infectious disease specialist at Brigham and Women’s Hospital in Boston. “That’s really what we’re looking forward to. Then you say, ‘Sure, I’ll take the chance of going to a restaurant. My chance of going to a restaurant and getting sick from Covid is no higher than the risk of getting sick from a regular cold.’ That’s a risk people should be very willing to take.”

“People have to keep their eyes on the Covid landscape the way they do the weather,” said Dr. Peter Chin-Hong, an infectious disease expert at the University of California, San Francisco. He recommended that people monitor vaccination rates in their community and cases per 100,000. Dr. Carlos del Rio, an infectious disease specialist at Emory University, recommended the Covid ActNow site to check case numbers per county; The New York Times also tracks risk level by county.

If your area has fewer than 10 cases per 100,000, it’s safer to go to a party or hang out indoors in a larger group of all vaccinated people. A far less safe scenario would be to participate in the kinds of spring break-related parties that are drawing attention in Florida, which reported 22 cases per 100,000 in the past seven days and is thought to have a large concentration of B.1.1.7, the more contagious and possibly more lethal virus variant first identified in Britain.

Can we make out with strangers?

Experts interviewed for this piece said that kissing and other intimate contact with someone you don’t know once you’ve been vaccinated is likely to be safe as long as you can confirm that they are also vaccinated.

Even without that confirmation, making out with a stranger is likely to be a lower risk activity than going into a crowded setting like a club or party, said Dr. David Rubin, a professor of pediatrics at the Perelman School of Medicine at the University of Pennsylvania. “It’s one of those events best left to the individual person, to make that choice and not judge it,” he said.

“If you’re in a controlled setting and you’re just with that person, and you want to take a chance on making out with that person and you think that person doesn’t have any risk of getting bad Covid — from the C.D.C. guidance, you can go ahead and make out with that person all you want,” said Dr. Chin-Hong.

If you’re vaccinated but can’t confirm the vaccination or medical status of the person you want to kiss, it will be OK for most young people, he said.

“The name of the game here is control,” he said. “The more noses and mouths that get together, the potentially riskier it is for transmission.”

There’s also the obvious logistical quandary: It can be hard to casually and quickly verify that someone is fully vaccinated and low-risk. One dating app, Coffee Meets Bagel, recently added an option to include vaccine status on dating profiles, although it does not require verification.

Can we gather in groups?

The C.D.C. released recommendations earlier this month that said that it’s safe for vaccinated adults to gather in small groups without masks or social distancing. A C.D.C. spokeswoman said in an email that those guidelines applied to all people living in the United States, and that there were no additional considerations for younger adults.

Practically, that means it’s OK for a group of about five to 10 vaccinated friends to hang out without precautions. But the larger the gathering, the more likely it is that someone in the group will be unvaccinated. While all three vaccines seem to be effective at preventing severe illness from the virus, we don’t yet know if they’ll prevent people from transmitting the virus to others.

What about indoor bars?

Dr. Ashish K. Jha, dean of the Brown University School of Public Health, predicted that most bars will be open across the country this summer. He also predicted that they’ll be a major source of viral spread among unvaccinated people, though they should be mostly safe for those who have received the vaccine.

“The bottom line is, if you want to go to a bar, you want to go to a club — you can, and you’ll be pretty safe” once you’ve been vaccinated, Dr. Jha said. But other experts cautioned that there are still too many unknowns — about variants, about whether you can still transmit the virus after you’ve been vaccinated — to fully encourage people to flock back to indoor bars.

Outdoor bars can be safer, depending on their setup and particularly if community transmission is low. Just be sure to stick to a small group of friends, rather than a large crowd.

What about outdoor concerts?

Experts agreed that outdoor concerts could be safe, particularly if attendees wear masks and keep distanced. Outdoor activities can support much larger groups of vaccinated people, Dr. Sax said.

“People were wondering why there weren’t more cases after the protests this summer,” he said. “Well, it’s because they took place outside. That’s going to be true about outdoor concerts, also — I’d be very surprised if there were any major spreader events linked to an outdoor concert.”

Do young people need to get vaccinated?

Experts expressed concerns about vaccine hesitancy among young people. In January, the U.S. Census Bureau released survey data that showed that Americans under 44 were most reluctant to get vaccinated.

“We’ve been selling the vaccine to older individuals as a way to protect against hospitalization and death,” Dr. del Rio said. “Most young people, if they get infected, they get a mild disease. We need to be able to communicate very clearly that there’s an advantage to getting the vaccine for young people, besides saying, ‘You’re not going to die.’”

“The faster we vaccinate people, the more likely we are to have a more normal life,” he said.

‘How Did You Qualify?’ For the Young and Vaccinated, Rude Questions and Raised Eyebrows

Medical privacy has become the latest casualty of vaccination efforts, as friends, co-workers and even total strangers ask intrusive questions about personal health conditions.

Peter Gamlen

When Helena Jenkins, 23, recently asked to leave work early for a vaccination appointment, her boss at a Nashville retail store was incredulous.

“Well how did you get that?” he asked.

Ms. Jenkins was embarrassed, but answered truthfully. “Um, my weight,” she stammered, referring to the fact that, in Tennessee, a body mass index of 30 qualified her for vaccination in early March. “I had a moment of ‘ugh,’” she said later. “It made me so uncomfortable, but it didn’t click until afterward that I definitely didn’t have to answer that.”

As public health officials push to get more at-risk people vaccinated, many of the newly qualified are discovering an unwelcome side effect of vaccination: Intrusive questions about their personal health.

The majority of states now have expanded vaccine eligibility to include people with underlying health conditions that put them at risk for complications from Covid-19, such as high blood pressure, a compromised immune system or obesity. As a result, the demographics of the vaccine waiting lines have shifted from mostly older people and now include many seemingly healthy people in their 20s, 30s and 40s. Young vaccine recipients say their friends and co-workers are intensely curious about the appointment process, and as a result, often ignore boundaries about personal health that they never would have crossed in the past. Some of them ask directly: “What health problem allowed you to qualify?”

When Amy Coody, 43, a mental health worker in Montgomery, Ala., told her friends and colleagues she had a vaccine appointment, she was shocked when it felt like people were judging her and assuming she had taken another person’s spot in line. Ms. Coody knows that she looks young and healthy, but she qualifies for two reasons — her work takes her into hospital settings, and she also has an underlying health condition that puts her at high risk.

“The hostility was definitely there,” she said. “They’d be like, ‘Wait, how did you get an appointment?’ I wasn’t prepared for that kind of reaction. It took me off guard so I eventually stopped telling people I planned to get the vaccine.”

Vaccine supply issues resulted in the cancellation of two of her appointments, and the shaming even made her debate rescheduling. “I would never want to step in front of somebody who needed it,” said Ms. Coody. “Then I realized, I do need it. There are a lot of patients in hospitals waiting for care. I thought, it’s about them. It’s not about me and my shame or anybody else who doesn’t understand the situation.”

Getting policed about a hidden health issue isn’t new to Ms. Coody, who has a condition called dysautonomia, a disorder of the autonomic nervous system that can cause her to suddenly pass out. She said the vaccine shaming she has experienced was similar to when she’s been confronted after parking in a handicapped space, even though she has a tag that allows her to park there.

“People come up to me and say, ‘You’re young and you obviously don’t have an illness so why are you taking a handicap spot?’” Ms. Coody said. “Even though it’s none of their business, I feel the need to defend myself. If more people realized there are invisible illnesses out there, maybe they might be a little more respectful about it.”

Even total strangers waiting in vaccine lines have felt justified in interrogating someone who looks young and healthy. Those on the receiving end of the questions say the implication is that they must have cheated and jumped the line.

Joanna Hua, 23 and a graduate student at Georgetown University, was standing in line for her second dose recently when an older woman she’d never met confronted her. “She looked at me and said, ‘You look very young to be getting the vaccine,’” Ms. Hua recounted. “She asked me, ‘How did you end up being able to qualify for one?’”

Ms. Hua said she was taken aback by the question. She told the woman truthfully that she qualified because she worked in a grocery store, but she didn’t mention that she also qualified based on her weight. She said another young woman in line near her also nervously explained her reasons for qualifying.

“I felt an instinctive need to justify myself,” said Ms. Hua. “It felt almost accusatory and invasive to ask about it. I think there is some sort of idea going around that people are just taking advantage and trying to get a vaccine whenever possible. I don’t doubt that some people do that. But to have a stranger come up and ask you?”

Tanmoy Lala Das, a medical and doctoral student in New York City, has been helping with vaccination efforts in Manhattan, giving shots to patients and helping as a patient navigator. He said overall the experience at vaccination centers has been upbeat, and everyone is collegial and happy to be there. But he has, on occasion, heard people asking others about personal health issues while waiting in line for their shots.

“I’ve overheard people ask, ‘So what brings you in today?’” Mr. Das said. “The less stigmatized conditions people are open to talking about. They’d laugh and say, “Oh, you know, diabetes.’ I think the ones who are more sensitive, they say, ‘Oh, I just got a spot.’”

It doesn’t help that many people know someone who has jumped the line by claiming to be a teacher or a smoker or lying about a health condition. In New York a fitness instructor got vaccinated by claiming to be an educator, and in Florida two women even “dressed up as grannies” to get the vaccine.

“I think in New York, people are trying to figure out these dynamics of are you getting the dose because it was left over, or a condition that qualifies you or did you lie about something,” said Mr. Das. “The honest reality is I know people who have cut the line and lied about things — 29-year-old people who have gotten vaccines who don’t have pre-existing conditions. But I think most people are not lying. The goal is to vaccinate everyone.”

Rhonda Wolfson, who lives in Toronto, said that in places where the vaccination process still is age-restricted, it has created a different privacy problem, casting light on the fact that a person is above a certain age. Ms. Wolfson qualified for a pilot vaccination program in Ontario for people aged 60 to 64, and she realized that talking about her vaccination would reveal her as a sexagenarian to people who thought she was younger.

“I have one friend in her 40s, and she knows I’m older, but she doesn’t know my exact age,” said Ms. Wolfson. “She’s never asked, and I’ve never offered. I spoke to her last week and in my excitement I mentioned, ‘OMG, I got vaccinated.’ I could almost hear her pause, ‘Oh, you’re that age.’”

In some circles, the stigma of early vaccination is even more concerning because it could dissuade at-risk people from getting the shot. In the gay community, for instance, a young person who gets vaccinated in the early group might be seen to be immunocompromised.

“In the gay community there is this assumption that if you are getting the vaccine right now you must be secretly H.I.V. positive,” said Mr. Das, who is gay. “It has become an assumption in the community that if you’re a gay and you post a picture of the vaccine card, you’re positive and haven’t told us. I always talk to my friends and tell them, ‘Don’t assume things.’”

Mr. Das said he is hopeful that any stigma or medical privacy issues associated with early vaccination will disappear once vaccine appointments are open to everyone. President Biden has urged all states to expand medical eligibility to the general population by May 1, and many states, including Alaska, Arizona, Georgia and Mississippi, have already made the change.

“The sooner we get to vaccinating everyone, I think this question of ‘Oh, what qualified you?’ will stop,” Mr. Das said. “Once that goes away hopefully these barriers will break down, and people won’t keep asking these very personal questions.”

Weekly Health Quiz: Weight Gain, Covid and Exercise

1 of 7

During pandemic lockdowns, Americans gained, on average, about how many pounds a month?

Half a pound

1 pound

2 pounds

4 pounds

2 of 7

Spread of coronavirus at the gym would likely be highest among people attending this type of group exercise class:

Pilates

Yoga

Strength training

Spin class

3 of 7

Too much high-intensity exercise resulted in signs of damage to these cell structures, the energy generators found in every cell:

Ribosomes

Mitochondria

Lysozymes

Centrioles

4 of 7

Doctors are exploring a possible link between Covid-19 and ringing in the ears, a medical condition known as:

Anosmia

Dysgeusia

Tinnitus

Otitis

5 of 7

True or false? Once you’ve been fully vaccinated against coronavirus, you are fully protected against symptoms of Covid.

True

False

6 of 7

A study of patients in California who suffered from long-haul Covid found that this proportion had no cough, fever or other symptoms in the first 10 days after testing positive for coronavirus:

A tenth

A quarter

A third

Half

7 of 7

This psychiatric condition, formerly known as multiple personality disorder and depicted in films like “Sybil” and “The Three Faces of Eve,” now goes by this name:

Schizoaffective disorder

Borderline personality disorder

Dissociative identity disorder

Post-traumatic stress disorder

Pfizer Begins Testing Its Vaccine in Young Children

Other drug makers have begun similar trials of their Covid-19 vaccines. If they work in children younger than 12 as expected, it will be easier for the U.S. to reach herd immunity.

Pfizer has begun testing its Covid-19 vaccine in children under 12, a significant step in turning back the pandemic. The trial’s first participants, a pair of 9-year-old twin girls, were immunized at Duke University in North Carolina on Wednesday.

Results from the trial are expected in the second half of the year, and the company hopes to vaccinate younger children early next year, said Sharon Castillo, a spokeswoman for the pharmaceutical company.

Moderna also is beginning a trial of its vaccine in children six months to 12 years of age. Both companies have been testing their vaccines in children 12 and older, and expect those results in the next few weeks.

AstraZeneca last month began testing its vaccine in children six months and older, and Johnson & Johnson has said it plans to extend trials of its vaccine to young children after assessing its performance in older children.

Immunizing children will help schools to reopen as well as help to end the pandemic, said Dr. Emily Erbelding, an infectious diseases physician at the National Institutes of Health who oversees testing of Covid-19 vaccines in special populations.

An estimated 80 percent of the population may need to be vaccinated for the United States to reach herd immunity, the threshold at which the coronavirus runs out of people to infect. Some adults may refuse to be vaccinated, and others may not produce a robust immune response.

Children under 18 account for about 23 percent of the population in the United States, so even if a vast majority of adults opt for vaccines, “herd immunity might be hard to achieve without children being vaccinated,” Dr. Erbelding said.

Pfizer had initially said it would wait for data from older children before starting trials of its vaccine in children under 12. But “we were encouraged by the data from the 12 to 15 group,” said Ms. Castillo, who did not elaborate on the results so far.

Scientists will test three doses of the Pfizer vaccine — 10, 20 and 30 micrograms — in 144 children. Each dose will be assessed first in children 5 through 11 years of age, then in children ages 2 through 4 years, and finally in the youngest group, six months to 2 years.

After determining the most effective dose, the company will test the vaccine in 4,500 children. About two-thirds of the participants will be randomly selected to receive two doses 21 days apart; the remaining will get two placebo shots of saline. The researchers will assess the children’s immune response in blood drawn seven days after the second dose.

“It sounds like a good plan, and it’s exciting that another Covid-19 vaccine is moving forward with trials in children,” said Dr. Kristin Oliver, a pediatrician and vaccine expert at Mount Sinai Hospital in New York.

Dr. Oliver said about half of the parents she sees in practice are eagerly waiting for vaccines, and even to volunteer their children for clinical trials, while the rest are skeptical because comparatively few children become seriously ill from coronavirus infection.

Both groups of parents will benefit from knowing exactly how safe and effective the vaccines are in children, she said.

Children represent 13 percent of all reported cases in the United States. More than 3.3 million children have tested positive for the virus, at least 13,000 have been hospitalized and at least 260 have died, noted Dr. Yvonne Maldonado, who represents the American Academy of Pediatrics on the federal Advisory Committee on Immunization Practices.

The figures do not fully capture the damage to children’s health. “We don’t know what the long-term effects of Covid infection are going to be,” Dr. Maldonado said.

Other vaccines have helped to control many horrific childhood diseases that can cause long-term complications, she added: “For some of us who’ve seen that, we don’t want to go back to those days.”

Children often react more strongly to vaccines than adults do, and infants and toddlers in particular can experience high fevers. Any side effects are likely to appear soon after the shot, within the first week and certainly within the first few weeks, experts have said.

Some vaccines are tested only in animals before being assessed in children, and have to be monitored carefully for side effects.

“But this is a little different, because we’ve already had experience with tens of millions of people with these vaccines,” Dr. Maldonado said. “So there’s a higher degree of confidence now in giving this vaccine to kids.”

Some experts suggested that the Food and Drug Administration may require up to six months of safety data from studies of children before authorizing the Covid-19 vaccines. But a spokeswoman said the agency did not expect six months of safety data to support the vaccines’ authorization.

The Pfizer-BioNTech vaccine is authorized for children 16 through 18 years old, and the authorization for that age group was based on just two months of safety data, she said.

Parents will want to know how the companies and the F.D.A. plan to monitor and disclose side effects from the vaccines, and how long they will continue to follow trial participants after the vaccines’ authorization, Dr. Oliver said.

“I think everyone has learned throughout this,” she said. “The more transparent you can be, the better.”

In Search of a Vaccine, Some Tourists Find Luck in the Caribbean

Roughly 3 percent of vaccines in the U.S. Virgin Islands have gone to tourists, the governor said this week. “Nowhere else in the U.S. can you actually just walk in and get the vaccine,” he said.

When Lydia Todman booked a trip to St. Croix with her husband earlier this month, she was hoping only for a relaxing getaway. But when she arrived, she learned she could also get the Covid-19 vaccine.

Ms. Todman, 43, said that local residents she knew on the island encouraged her to book a vaccine appointment. At the time, she and her husband, who is 64 and has asthma, were not eligible for a shot in their home state, Georgia. But in St. Croix, every adult is eligible. So she visited the territory’s Department of Health website, saw they had appointments available for the next day, and signed up.

“We were in and out within a matter of a few minutes,” Ms. Todman said. “It was amazing.”

Nearly 106,000 people call the U.S. Virgin Islands home, and the territory has administered more than 33,000 Covid-19 vaccines to date, with about 10,600 people now fully protected with two doses. At a news briefing on Monday, the governor, Albert Bryan Jr., estimated that at most 3 percent, or approximately 1,000 of those vaccines, have gone to tourists.

“Have we become aware of the fact that people are seeking us out? Yes. And you know, we accommodate everyone,” said Angela East, the coordinator and director of the Covid-19 vaccine program at Plessen Healthcare, which has administered 44 percent of all Covid-19 vaccines in the territory. “We are going to give you the shot in the spirit of putting as many shots in arms as possible.”

Health authorities and ethicists don’t see a big problem with the vaccine tourism in the U.S. Virgin Islands, given the ample supply of the shots and high levels of vaccine hesitancy among residents there. And the trend may wane as more U.S. states open up their eligibility criteria. Still, wealthy Americans traveling to the Caribbean to secure Covid-19 vaccines is an example of the many ways in which vaccine access across the world is shaped by race, circumstance and privilege.

In St. Croix, St. John and St. Thomas, the three largest of the U.S. Virgin Islands, vaccines are readily available to tourists partly because of vaccine hesitancy, “which is very high in the Virgin Islands,” said Dr. Tai Hunte-Ceasar, the medical director of the territory’s Department of Health. This hesitancy seems most pronounced among residents of color, Mr. Bryan said at the news briefing. “Caucasians that live in the Virgin Islands are more apt to take the vaccine and take it quicker,” he said.

When Bridget Platten, 40, who works in sales in New York City, received her Covid-19 vaccine in St. Croix, she was encouraged to tell friends to get inoculated, too. “The doctor said: ‘Listen, I have all this vaccine. And people are afraid to get it here,’” Ms. Platten recalled. “‘If you have any friends, or there’s anyone you know who wants a vaccine, please have them call me.’”

A pop-up coronavirus testing site by the U.S. Virgin Islands Department of Health in a parking lot in Charlette Amalie on Saint Thomas last month.
A pop-up coronavirus testing site by the U.S. Virgin Islands Department of Health in a parking lot in Charlette Amalie on Saint Thomas last month.Gabby Jones for The New York Times

Some Americans have flown to the island specifically to be vaccinated. “My friends from New Jersey went, and the most probing question they faced was, ‘Will that be Pfizer or Moderna for you?’” said Rob DeRocker, a marketing consultant from Tarrytown, N.Y., who spends winters in St. Croix. “The result has been a mini boom of visitors on an island whose tourism economy, like most others, has been brutalized by the pandemic.”

This boom has been aided by the fact that since March 1, everyone over 16 has been eligible to get the vaccine in the Virgin Islands — so tourists don’t even have to worry about cutting in line. The territory accommodates about 100 walk-ins each day, too. “Nowhere else in the U.S. can you actually just walk in and get the vaccine, anybody over 16,” Mr. Bryan said on Monday. On March 1, the islands also opened two federally supported community vaccination centers on St. Thomas and St. Croix.

U.S. travelers also face less red tape when visiting the U.S. Virgin Islands compared with other Caribbean destinations. If they submit a negative coronavirus test within five days of leaving for the territory, or a positive antibody test taken within four months, they do not have to quarantine upon arrival. Travelers to Jamaica and Barbados, in contrast, are asked to quarantine no matter what. And U.S. travelers can’t visit the Cayman Islands unless they conform to strict eligibility criteria.

Dr. Hunte-Ceasar said that, at this point, the Department of Health did not consider vaccine tourism to be a problem. “We definitely want to ensure the local residents get vaccinated,” she said. But “we have not had any shortages by serving both populations.” The Virgin Islands currently have 27,000 doses of the Pfizer vaccine, 18,900 doses of the Moderna vaccine, and 600 doses of the Johnson & Johnson vaccine available, said Monife Stout, the department’s immunization director.

Noreen Michael, a scientist at the University of the Virgin Islands who studies health disparities, agreed that it was crucial to ensure that vaccines are available to residents who want them, but said she had not seen evidence to suggest that tourists are taking vaccines away from residents who want them. “On the public health side, it’s a plus,” she said. “On the equity side, I don’t see it as significant issue.”

Perhaps, too, vaccine tourism could be used as a force for good — to secure doses for marginalized groups in other regions. Although the Virgin Islands provide free Covid-19 vaccines, the islands could charge tourists for their vaccines, and the funds could be used to send vaccines to regions that need them, said Felicia Knaul, an international health economist at the University of Miami. “Could we send those vaccines to Jamaica, or to the Dominican Republic or Haiti?” she asked. “Once you’ve gotten past the key welfare and human rights aspects, if you can use that funding to pay for people who right now have no access, I think it’s worth thinking about.”

For now, health authorities are focused on ways to reduce vaccine hesitancy in the territory. “People access misinformation and perpetuate lies and things that are harmful,” Dr. Hunte-Ceasar said in a news conference last week. As a result, the islands have been experiencing a surge in cases and hospitalizations that she said give her “chest pain and heartburn every night.” Although vaccine hesitancy does seem to be decreasing, residents will need to start widely embracing the vaccine if the islands are to meet their goal of vaccinating 50,000 Virgin Islanders by July 1.

In the meantime, visitors from the continental U.S. will continue to take advantage of the extra doses. Some have stayed longer than they planned, too — and have even contemplated moving to the islands for good.

“I started falling in love with the culture of St. Croix,” said Hemal Trivedi, a documentary filmmaker who lives in Weehawken, N.J., and was vaccinated in St. Croix in February. “Toward the end of the trip, we were actually looking for a place to buy.”

Vaccinated People Can Get Covid, but It’s Most Likely Very Rare

“Breakthrough” cases, though quite uncommon, are a sharp reminder that vaccinated people should wear masks while the virus is circulating widely.

More than two months after he was fully vaccinated against Covid, a doctor in New York woke up with a headache and a dull, heavy feeling of fatigue. A fever and chills soon followed, and his senses of taste and smell began to fade.

This, he thought, could not be happening. But it was: He tested positive for the coronavirus.

“It was a huge shock,” he said. He knew that no vaccine was perfect and that the Pfizer-BioNTech shots he received had been found 95 percent effective in a large clinical trial. “But somehow in my mind, it was 100 percent,” he said.

The doctor, who requested anonymity to protect his privacy, is among the few reported cases of people who have been infected after being partly or even fully vaccinated. Nearly 83 million Americans have received at least one dose of a Covid vaccine, and it’s unclear just how many of them will have a “breakthrough” infection, though two new reports suggest the number is very small.

One study found that just four out of 8,121 fully vaccinated employees at the Southwestern Medical Center in Dallas became infected. The other found that only seven out of 14,990 workers at UC San Diego Health and the David Geffen School of Medicine at the University of California, Los Angeles tested positive two or more weeks after receiving a second dose of either the Pfizer-BioNTech or Moderna vaccines. Both reports, published on Tuesday in the New England Journal of Medicine, show how well the vaccines work in the real world, and during a period of intense transmission.

But these breakthrough cases, though quite rare, are a sharp reminder that vaccinated people are not invincible, especially when the virus continues to circulate widely.

“We felt really strongly that this data should not lead people to say, ‘Let’s all get vaccinated and then we can all stop wearing masks,’” said Dr. Francesca J. Torriani, an infectious disease specialist at UC San Diego Health who led the California study. “These measures have to continue until a larger segment of the population is vaccinated.”

Only some of the Covid-positive health workers in the California study showed symptoms, she said, and they tended to be mild, suggesting that the vaccines were protective. That echoes data from the vaccine trials indicating that breakthrough infections were mild and did not require hospitalizations. Some people had no symptoms at all, and were discovered only through testing in studies or as part of their medical care.

For example, doctors at the University of North Carolina found a few asymptomatic cases in vaccinated patients who were tested for the coronavirus ahead of surgery or other medical procedures, according to Dr. David Wohl, the medical director of that center’s vaccine clinic.

He said the absence of symptoms may have meant that the vaccine was doing exactly what it is supposed to do: prevent people from getting sick, even if it does not fully block the virus from infecting them.

The Centers for Disease Control and Prevention has a small team studying breakthrough cases, said an agency spokeswoman, Kristen Nordlund. One question the researchers are considering is whether particular variants of the coronavirus might play a role in breakthrough cases.

“Currently, there is no evidence that Covid-19 after vaccination is occurring because of changes in the virus,” Ms. Nordlund said.

In the next few months, Pfizer and Moderna are expected to release data that should indicate how often vaccinated people become infected by the virus, even if they have no symptoms. The companies have been testing participants in their vaccine trials for antibodies to a protein called N that is part of the coronavirus but not part of the vaccine. Finding those antibodies means that a vaccinated person has been infected by the virus. Some volunteers from the studies are also having their noses swabbed regularly to test for an active viral infection.

Another question is how effective the vaccines are in people whose immune systems have been weakened by illness or medications, said Dr. William Schaffner, an infectious disease expert at Vanderbilt University. Breakthrough cases might occur in those people because their bodies cannot produce a robust reaction to a vaccine.

“And it is amazing how pervasive immunocompromise is,” Dr. Schaffner said. He called the condition “a testament to modern medicine,” because many patients with it are being treated successfully for conditions that not so long ago would have killed them.

The doctor who became ill in New York despite full vaccination stayed in isolation at home for nearly two weeks. He described his illness as relatively mild, and said he was treated with monoclonal antibodies to fight the virus. “If the worst flu is a 10, this was a four,” he said.

Without the vaccine, he said, he believes he would have been sicker.

“I would have been in fear for my mortality,” he said. “But I didn’t have a moment’s anxiety. I did not think I was going to die. Thinking you’re not going to die — that’s a pretty big thing.”

Apoorva Mandavilli contributed reporting.

Weekly Health Quiz: Covid Vaccines, Microbiomes and How We Move

1 of 7

Which statement about the way we move is supported by research?

Romantic couples unconsciously tend to synchronize their walking pace

Pet dogs tend to synchronize their movements with family members

People who taking up dancing tend to feel greater degrees of closeness

All of the above

2 of 7

About what percentage of Americans have received at least one Covid vaccine shot?

5 percent

12 percent

23 percent

52 percent

3 of 7

About what percentage of Americans expressed anxiety about resuming in-person interactions once the pandemic eases?

10 percent

25 percent

50 percent

75 percent

4 of 7

Compared to those whose gut microbiome stays relatively stable over time, those whose microbiome changes over the decades tend to:

Have shorter life spans

Live longer

The microbiome has little relationship with how successfully you age

5 of 7

Which statement about maple syrup urine disease is not true?

The name comes from the distinctive smell of urine and sweat

It is a rare genetic disorder that can run in families

Symptoms include periods of disorientation and confusion

People with the disorder must eat a high-protein diet

6 of 7

Researchers believe that a current outbreak of Ebola in Guinea was likely caused by a survivor of West Africa’s 2014-16 epidemic who harbored the virus for at least five years and then transmitted it via:

Respiratory droplets

Blood transfusion

Semen

Saliva

7 of 7

Fred Figa, a pharmacist, died recently from coronavirus complications. He is perhaps best known for alerting people to the dangers of an unregulated injection of this vitamin that caused the deaths of 38 infants in the 1980s:

Vitamin A

Vitamin C

Vitamin D

Vitamin E

Coronavirus Reinfections Are Rare, Danish Researchers Report

People over 65 are more likely to experience a second bout with the virus, according to a large study of medical records.

The vast majority of people who recover from Covid-19 remain shielded from the virus for at least six months, researchers reported on Wednesday in a large study from Denmark.

Prior infection with the coronavirus reduced the chances of a second bout by about 80 percent in people under 65, but only by about half in those older than 65. But those results, published in the journal Lancet, were tempered by many caveats.

The number of infected older people in the study was small. The researchers did not have any information beyond the test results, so it’s possible that only people who were mildly ill the first time became infected again and that the second infections were largely symptom-free.

Scientists have said that reinfections are likely to be asymptomatic or mild because the immune system will suppress the virus before it can do much damage. The researchers also did not assess the possibility of reinfection with newer variants of the virus.

Still, the study suggests that immunity to a natural infection is unpredictable and uneven, and it underscores the importance of vaccinating everyone — especially older people, experts said.

“You can certainly not rely on a past infection as protecting you from being ill again, and possibly quite ill if you are in the elderly segment,” said Steen Ethelberg, an epidemiologist at Statens Serum Institut, Denmark’s public health agency.

Because people over 65 are at highest risk of severe disease and death, he said, “they are the ones we are most eager to protect.”

Rigorous estimates of second infections have generally been rare because many people worldwide did not initially have access to testing, and laboratories require genetic sequences from both rounds of testing to confirm a reinfection.

But the findings are consistent with those from experiments in a wide variety of settings: sailors on a fishing trawler in Seattle, Marine Corps recruits in South Carolina, health care workers in Britain and patients at clinics in the United States.

The new study’s design and size benefited from Denmark’s free and abundant testing for the coronavirus. Nearly 70 percent of the country’s population was tested for the virus in 2020.

The researchers looked at the results from 11,068 people who tested positive for the coronavirus during the first wave in Denmark between March and May 2020. During the second wave, from September to December, 72 of those people, or 0.65 percent, again tested positive, compared with 3.27 percent of people who became infected for the first time.

That translates to a 80 percent protection from the virus in those who had been infected before. The protection fell to 47 percent for those over 65. The team also analyzed test results from nearly 2.5 million people throughout the epidemic, some longer than seven months after the first infection, and found similar results.

“It was really nice to see that there was no difference in protection from reinfection over time,” said Marion Pepper, an immunologist at the University of Washington in Seattle.

She and other experts noted that while 80 percent might not seem superb, protection from symptomatic illness was likely to be higher. The analysis included anyone who was tested, regardless of symptoms.

“A lot of these will be asymptomatic infections, and a lot of these will likely be people who have a blip of virus,” noted Florian Krammer, an immunologist at the Icahn School of Medicine at Mount Sinai in New York. “Eighty percent risk reduction against asymptomatic infection is great.”

The findings indicate that people who have recovered from Covid-19 should get at least one dose of a coronavirus vaccine to boost the level of protection, Dr. Krammer added. Most people produce robust immune response to a natural infection, “but there’s a lot of variability,” he said. Following vaccination, “we don’t see variability — we see very high responses in basically everybody, with very few exceptions.”

Experts were less convinced by the results in people over 65, saying the findings would have been more robust if the analysis had included more people from that age group.

“I wish it had actually been broken down into specific decades over 65,” Dr. Pepper said. “It would be nice to know whether the majority of people who were getting reinfected were over 80.”

The immune system grows progressively weaker with age, and people over 80 typically mount weak responses to infection with a virus. The lower protection in older people seen in the study is consistent with those observations, said Akiko Iwasaki, an immunologist at Yale University.

“I think we kind of tend to forget how the vaccines have been pretty amazing in offering protection in this age group, because you can see that natural infection doesn’t confer the same kind of protection,” she said. “This really does emphasize the need to cover older people with the vaccine, even if they have had Covid first.”

Some Long Covid-19 Patients Feel Better After Vaccine Doses

It is too soon to tell whether the shots have a broad beneficial effect on patients with continuing issues, but scientists are intrigued and beginning to study the phenomenon.

Judy Dodd began struggling with long Covid symptoms last spring — shortness of breath, headaches, exhaustion. Then she got the vaccine.

After her first Pfizer-BioNTech shot in late January, she felt so physically miserable that she had to be persuaded to get the second. For three days after that one, she also felt awful. But the fourth day, everything changed.

“I woke up and it was like ‘Oh what a beautiful morning,’” said Ms. Dodd, a middle-school teacher who is also an actor and director. “It was like I’d been directing ‘Sweeney Todd’ for months, and now I’m directing Oklahoma.”

Ms. Dodd, who continues to feel good, is among a number of people who are reporting that the post-Covid symptoms they’ve experienced for months have begun improving, sometimes significantly, after they got the vaccine. It’s a phenomenon that doctors and scientists are watching closely, but as with much about the yearlong coronavirus pandemic, there are many uncertainties.

Scientists are only beginning to study any potential effect of vaccines on long Covid symptoms. Anecdotes run the gamut: Besides those who report feeling better after the shots, many people say they have experienced no change and a small number say they feel worse.

Reports from doctors vary too. Dr. Daniel Griffin, an infectious disease physician at Columbia University, said about 40 percent of the long Covid patients he’s been treating cite symptom improvement after the vaccine. “They notice, ‘Hey, over the days, I’m feeling better. The fatigue isn’t so bad, maybe smell is coming back,’” Dr. Griffin said.

Other doctors say it is too early to know.

“Too few of our participants have been vaccinated so far to really be able to provide insight into this question,” said Dr. Michael Peluso, an infectious disease specialist working on a study of long-term Covid patients at University of California, San Francisco. “I’ve heard anecdotes as well, but I’ve seen too little data so far.”

This month, a small study by British researchers that has not yet been peer reviewed found that eight months after people were hospitalized for Covid-19, those who were vaccinated experienced improvement in more long Covid symptoms than those who weren’t yet vaccinated. The 44 vaccinated patients in the study were older and had more underlying medical conditions, since people with those characteristics qualified for vaccines earlier.

One month after vaccination, those patients reported improvement in 23 percent of their long Covid symptoms like joint pain and breathing, while 5.6 percent of their symptoms had worsened. The 22 unvaccinated people questioned at that time said 15 percent of their symptoms were better, while 14 percent of their symptoms were worse. There was no difference in response between people who received the Pfizer-BioNTech and Oxford-AstraZeneca vaccines.

Additional information comes from two surveys of several hundred people with long Covid symptoms, many of whom were never hospitalized for the disease.

Jim Golen, a former hospice nurse in Saginaw, Minn. He said his long Covid symptoms have gotten worse since his vaccination, but he’s still glad he got the vaccine.
Jim Golen, a former hospice nurse in Saginaw, Minn. He said his long Covid symptoms have gotten worse since his vaccination, but he’s still glad he got the vaccine.Tim Gruber for The New York Times

One survey of 345 people, mostly women and mostly in the U.K., found that two weeks or more after their second vaccine dose, 93 felt slightly better and 18 felt back to normal — a total of 32 percent reporting improved long Covid symptoms.

In that survey, by Gez Medinger, a London-based filmmaker who has experienced post-Covid symptoms, 61 people, just under 18 percent, felt worse, most of them reporting only a slight decline in their condition. Nearly half — 172 people — reported feeling no different.

Another survey, by Survivor Corps, a group of over 150,000 Covid survivors, found that as of March 17, 225 of 577 respondents reported some improvement, while 270 felt no change and 82 felt worse.

Jim Golen, 55, of Saginaw, Minn., feels some long Covid symptoms have worsened since his vaccination. Mr. Golen, a former hospice nurse who also has a small farm, had experienced months of difficulty, including blood clots in his lungs, chest pain, brain fog, insomnia and shortness of breath with any exertion. Late last year, after seeing several doctors, “I was finally starting to get better,” he said.

Since receiving the second dose of the Pfizer vaccine in mid-January, he said, his chest burning and shortness of breath have returned with a vengeance, especially if he taxes himself with activities like collecting sap from the maple trees on his farm. Nonetheless, Mr. Golen said he was “very happy” to be vaccinated, emphasizing that the effects of Covid were worse and preventing it is crucial.

Some people shared stories of stark symptom improvements that took them by surprise.

Laura Gross, 72, of Fort Lee, N.J. rattled off a lengthy list of debilitating long Covid symptoms she’d experienced since April, including exhaustion, joint pain, muscle aches and a “zizzy-dizzy-weaky thing that was like an internal headachy all-over-body vibration.”

Her cognitive fuzziness and forgetfulness were so intense that “brain fog barely describes it,” she said. “It’s more like brain cyclone.”

She also felt uncharacteristically “hopeless, sad, lonely, unmotivated,” she said.

Three days after her first Moderna shot in late January, everything changed. “It was like a revelation,” she said. The brain fog cleared completely, muscle aches were gone, joint pains were less intense and she suddenly had much more energy. It felt, she said, “like the old me.”

That continued after the second dose. “It’s like my cells went kerflooey last year when they met Covid,” she said, and the “vaccine said, ‘Wait, you dopes, that isn’t how you fight this, do it this way.’”

Recently, she walked briskly for 23 minutes and even “ran a little bit because I was so happy,” she said. “I’m a very happy little chappy.”

Laura Gross of Fort Lee, N.J., said brain fog is inadequate in describing her symptoms: “It’s more like brain cyclone,” she said. She reports feeling much better since being vaccinated.Nancy Borowick for The New York Times

Scientists say that understanding whether vaccines help some long Covid patients but not others could help unravel the underlying causes of different symptoms and potential ways to treat them.

“They might be different disease processes and you manage them differently,” said Dr. Adam Lauring, a virologist and infectious disease physician at the University of Michigan. “It might be that there’s a subset of people who have a certain type of long Covid, who respond well to vaccines, but there might be other people who have a different subtype that we haven’t quite defined yet.”

Akiko Iwasaki, an immunologist at Yale, said that a vaccine, by generating antibodies to the coronavirus’s spike protein, could potentially eliminate vestiges of the virus or remnants of viral RNA that may linger in some patients.

If this is occurring, she said, it could suggest that the vaccine “might be like a permanent cure” for those patients.

Dr. Iwasaki said the vaccine might also help people whose long Covid symptoms may be caused by a post-viral response resembling an autoimmune disease if “the vaccine stimulates innate immune responses that dampen these kinds of autoreactive responses,” she said. But based on experiences of people with other autoimmune diseases, that relief would “not be very long-lasting and they would kind of revert back” to having symptoms like fatigue, she said.

Dr. Eric Topol, a professor of molecular medicine at the Scripps Research Institute in San Diego, said he is starting a study to measure physiological information like heart rate, respiratory rate, temperature and markers of immune system response in people with long Covid before they receive a vaccine and weeks afterward.

It’s plausible that “you have your immune system revved up when you’re fighting a reservoir” of virus or RNA remnants, he said, “and that could be an explanation of why you’re in overdrive with your heart rate.” He wants to see if these biological indicators improve post-vaccine.

“We’d really like objective metrics that show that you not just feel better,” Dr. Topol said. “You could feel better from the placebo effect, but it’s unlikely your heart rate’s going to go from 100 to 60 because of a placebo effect. And if we keep seeing that pattern, that would be like Eureka.”

He added, “I think there’s probably something there, but I just don’t know what is the magnitude, how many people are going to benefit.”

There are many other questions: Are there specific characteristics, like age, gender, type or duration of symptoms, that might make some long Covid patients more likely to feel better? Would a vaccine be less effective for people with more complex conditions: people whose symptoms are driven by multiple biological pathways (perhaps both an RNA remnant and autoimmune activation) or whose symptoms have changed or fluctuated over time? Are certain types of vaccines more likely to produce benefit?

“It was awful thinking it may never get better, like ‘Is this my new normal, am I now damaged this way?’” recalled Bridget Hayward of her symptoms, which she says have eased since her vaccination.Alyssa Schukar for The New York Times

Bridget Hayward, 51, an operating room nurse in Alexandria, Va., said that after contracting Covid a year ago, her body ached from her hands to her hips and she became so brain-fogged that instead of asking for a scalpel, she would say “Give me that sharp thing we cut with.”

Almost daily, she would briefly pass out while bending down to fix a patient’s intravenous line or plug in the cord of a hospital bed.

“It was horrifying,” she said. “It was awful thinking it may never get better, like ‘Is this my new normal, am I now damaged this way?’”

After several months, her worst symptoms improved, but she still tired easily, felt hot even in cool weather, and found it too taxing to do some ordinary tasks, she said.

One day after her first dose of the Pfizer vaccine in late December, “it was like click, everything is fine,” she said. Her body temperature has normalized and “it felt like a darkness lifted.”

While “it’s not 100 percent every day,” she said she has so much energy now that “I’m not just getting from A to B, I’m like leaping up.”

One recent day, she did several long-overdue errands. “This may not sound like much but it is a 180-turnaround from three months ago,” she said. “I’m back!”

Kim Leighton, 64, of Vancouver, Wash., has had a similar experience. She was hospitalized last March and had long Covid symptoms that included mini blackouts, shortness of breath, getting lost in her own neighborhood, depression and fatigue.

“It really has been hell,” she said.

When she started feeling better in late January, she didn’t even think to connect it to the vaccine, but later realized her stark improvement had started four days after receiving her first Moderna shot. She is delighted that she can now take walks in downtown Portland and has the desire to reconnect with friends.

“Every day, I feel like I’m feeling stronger,” Ms. Leighton said. “All the stuff I had to let go of, I’m trying to get it back.”

Ms. Dodd, like several others, said she wasn’t taking her improvement for granted. “I’m still sort of wary of what’s around the corner, this disease is so unpredictable,” she said.

But, she added, “even if, God forbid, I have a relapse, to have this time now when I feel better, it’s really amazing.”

Some Long Covid Patients Feel Better After Getting the Vaccine

It is too soon to tell whether the shots have a broad beneficial effect on patients with continuing issues, but scientists are intrigued and beginning to study the phenomenon.

Judy Dodd began struggling with long Covid symptoms last spring — shortness of breath, headaches, exhaustion. Then she got the vaccine.

After her first Pfizer-BioNTech shot in late January, she felt so physically miserable that she had to be persuaded to get the second. For three days after that one, she also felt awful. But the fourth day, everything changed.

“I woke up and it was like ‘Oh what a beautiful morning,’” said Ms. Dodd, a middle-school teacher who is also an actor and director. “It was like I’d been directing ‘Sweeney Todd’ for months, and now I’m directing Oklahoma.”

Ms. Dodd, who continues to feel good, is among a number of people who are reporting that the post-Covid symptoms they’ve experienced for months have begun improving, sometimes significantly, after they got the vaccine. It’s a phenomenon that doctors and scientists are watching closely, but as with much about the yearlong coronavirus pandemic, there are many uncertainties.

Scientists are only beginning to study any potential effect of vaccines on long Covid symptoms. Anecdotes run the gamut: Besides those who report feeling better after the shots, many people say they have experienced no change and a small number say they feel worse.

Reports from doctors vary too. Dr. Daniel Griffin, an infectious disease physician at Columbia University, said about 40 percent of the long Covid patients he’s been treating cite symptom improvement after the vaccine. “They notice, ‘Hey, over the days, I’m feeling better. The fatigue isn’t so bad, maybe smell is coming back,’” Dr. Griffin said.

Other doctors say it is too early to know.

“Too few of our participants have been vaccinated so far to really be able to provide insight into this question,” said Dr. Michael Peluso, an infectious disease specialist working on a study of long-term Covid patients at University of California, San Francisco. “I’ve heard anecdotes as well, but I’ve seen too little data so far.”

This month, a small study by British researchers that has not yet been peer reviewed found that eight months after people were hospitalized for Covid-19, those who were vaccinated experienced improvement in more long Covid symptoms than those who weren’t yet vaccinated. The 44 vaccinated patients in the study were older and had more underlying medical conditions, since people with those characteristics qualified for vaccines earlier.

One month after vaccination, those patients reported improvement in 23 percent of their long Covid symptoms like joint pain and breathing, while 5.6 percent of their symptoms had worsened. The 22 unvaccinated people questioned at that time said 15 percent of their symptoms were better, while 14 percent of their symptoms were worse. There was no difference in response between people who received the Pfizer-BioNTech and Oxford-AstraZeneca vaccines.

Additional information comes from two surveys of several hundred people with long Covid symptoms, many of whom were never hospitalized for the disease.

Jim Golen, a former hospice nurse in Saginaw, Minn. He said his long Covid symptoms have gotten worse since his vaccination, but he’s still glad he got the vaccine.
Jim Golen, a former hospice nurse in Saginaw, Minn. He said his long Covid symptoms have gotten worse since his vaccination, but he’s still glad he got the vaccine.Tim Gruber for The New York Times

One survey of 345 people, mostly women and mostly in the U.K., found that two weeks or more after their second vaccine dose, 93 felt slightly better and 18 felt back to normal — a total of 32 percent reporting improved long Covid symptoms.

In that survey, by Gez Medinger, a London-based filmmaker who has experienced post-Covid symptoms, 61 people, just under 18 percent, felt worse, most of them reporting only a slight decline in their condition. Nearly half — 172 people — reported feeling no different.

Another survey, by Survivor Corps, a group of over 150,000 Covid survivors, found that as of March 16, 207 of 508 respondents reported some improvement, while 231 felt no change and 70 felt worse.

Jim Golen, 55, of Saginaw, Minn., feels some long Covid symptoms have worsened since his vaccination. Mr. Golen, a former hospice nurse who also has a small farm, had experienced months of difficulty, including blood clots in his lungs, chest pain, brain fog, insomnia and shortness of breath with any exertion. Late last year, after seeing several doctors, “I was finally starting to get better,” he said.

Since receiving the second dose of the Pfizer vaccine in mid-January, he said, his chest burning and shortness of breath have returned with a vengeance, especially if he taxes himself with activities like collecting sap from the maple trees on his farm. Nonetheless, Mr. Golen said he was “very happy” to be vaccinated, emphasizing that the effects of Covid were worse and preventing it is crucial.

Some people shared stories of stark symptom improvements that took them by surprise.

Laura Gross, 72, of Fort Lee, N.J. rattled off a lengthy list of debilitating long Covid symptoms she’d experienced since April, including exhaustion, joint pain, muscle aches and a “zizzy-dizzy-weaky thing that was like an internal headachy all-over-body vibration.”

Her cognitive fuzziness and forgetfulness were so intense that “brain fog barely describes it,” she said. “It’s more like brain cyclone.”

She also felt uncharacteristically “hopeless, sad, lonely, unmotivated,” she said.

Three days after her first Moderna shot in late January, everything changed. “It was like a revelation,” she said. The brain fog cleared completely, muscle aches were gone, joint pains were less intense and she suddenly had much more energy. It felt, she said, “like the old me.”

That continued after the second dose. “It’s like my cells went kerflooey last year when they met Covid,” she said, and the “vaccine said, ‘Wait, you dopes, that isn’t how you fight this, do it this way.’”

Recently, she walked briskly for 23 minutes and even “ran a little bit because I was so happy,” she said. “I’m a very happy little chappy.”

Laura Gross of Fort Lee, N.J., said brain fog is inadequate in describing her symptoms: “It’s more like brain cyclone,” she said. She reports feeling much better since being vaccinated.Nancy Borowick for The New York Times

Scientists say that understanding whether vaccines help some long Covid patients but not others could help unravel the underlying causes of different symptoms and potential ways to treat them.

“They might be different disease processes and you manage them differently,” said Dr. Adam Lauring, a virologist and infectious disease physician at the University of Michigan. “It might be that there’s a subset of people who have a certain type of long Covid, who respond well to vaccines, but there might be other people who have a different subtype that we haven’t quite defined yet.”

Akiko Iwasaki, an immunologist at Yale, said that a vaccine, by generating antibodies to the coronavirus’s spike protein, could potentially eliminate vestiges of the virus or remnants of viral RNA that may linger in some patients.

If this is occurring, she said, it could suggest that the vaccine “might be like a permanent cure” for those patients.

Dr. Iwasaki said the vaccine might also help people whose long Covid symptoms may be caused by a post-viral response resembling an autoimmune disease if “the vaccine stimulates innate immune responses that dampen these kinds of autoreactive responses,” she said. But based on experiences of people with other autoimmune diseases, that relief would “not be very long-lasting and they would kind of revert back” to having symptoms like fatigue, she said.

Dr. Eric Topol, a professor of molecular medicine at the Scripps Research Institute in San Diego, said he is starting a study to measure physiological information like heart rate, respiratory rate, temperature and markers of immune system response in people with long Covid before they receive a vaccine and weeks afterward.

It’s plausible that “you have your immune system revved up when you’re fighting a reservoir” of virus or RNA remnants, he said, “and that could be an explanation of why you’re in overdrive with your heart rate.” He wants to see if these biological indicators improve post-vaccine.

“We’d really like objective metrics that show that you not just feel better,” Dr. Topol said. “You could feel better from the placebo effect, but it’s unlikely your heart rate’s going to go from 100 to 60 because of a placebo effect. And if we keep seeing that pattern, that would be like Eureka.”

He added, “I think there’s probably something there, but I just don’t know what is the magnitude, how many people are going to benefit.”

There are many other questions: Are there specific characteristics, like age, gender, type or duration of symptoms, that might make some long Covid patients more likely to feel better? Would a vaccine be less effective for people with more complex conditions: people whose symptoms are driven by multiple biological pathways (perhaps both an RNA remnant and autoimmune activation) or whose symptoms have changed or fluctuated over time? Are certain types of vaccines more likely to produce benefit?

“It was awful thinking it may never get better, like ‘Is this my new normal, am I now damaged this way?’” recalled Bridget Hayward of her symptoms, which she says have eased since her vaccination.Alyssa Schukar for The New York Times

Bridget Hayward, 51, an operating room nurse in Alexandria, Va., said that after contracting Covid a year ago, her body ached from her hands to her hips and she became so brain-fogged that instead of asking for a scalpel, she would say “Give me that sharp thing we cut with.”

Almost daily, she would briefly pass out while bending down to fix a patient’s intravenous line or plug in the cord of a hospital bed.

“It was horrifying,” she said. “It was awful thinking it may never get better, like ‘Is this my new normal, am I now damaged this way?’”

After several months, her worst symptoms improved, but she still tired easily, felt hot even in cool weather, and found it too taxing to do some ordinary tasks, she said.

One day after her first dose of the Pfizer vaccine in late December, “it was like click, everything is fine,” she said. Her body temperature has normalized and “it felt like a darkness lifted.”

While “it’s not 100 percent every day,” she said she has so much energy now that “I’m not just getting from A to B, I’m like leaping up.”

One recent day, she did several long-overdue errands. “This may not sound like much but it is a 180-turnaround from three months ago,” she said. “I’m back!”

Kim Leighton, 64, of Vancouver, Wash., has had a similar experience. She was hospitalized last March and had long Covid symptoms that included mini blackouts, shortness of breath, getting lost in her own neighborhood, depression and fatigue.

“It really has been hell,” she said.

When she started feeling better in late January, she didn’t even think to connect it to the vaccine, but later realized her stark improvement had started four days after receiving her first Moderna shot. She is delighted that she can now take walks in downtown Portland and has the desire to reconnect with friends.

“Every day, I feel like I’m feeling stronger,” Ms. Leighton said. “All the stuff I had to let go of, I’m trying to get it back.”

Ms. Dodd, like several others, said she wasn’t taking her improvement for granted. “I’m still sort of wary of what’s around the corner, this disease is so unpredictable,” she said.

But, she added, “even if, God forbid, I have a relapse, to have this time now when I feel better, it’s really amazing.”

Moderna Starts Testing Its Covid Vaccine in Babies and Young Children

The company will study its vaccine in children ages six months through 11 in the United States and Canada.

The drug company Moderna has begun a study that will test its Covid vaccine in children under 12, including babies as young as six months, the company said on Tuesday.

The study is expected to enroll 6,750 healthy children in the United States and Canada. Moderna declined to say how many had already signed up or received the first shots, according to a spokeswoman, Colleen Hussey.

“There’s a huge demand to find out about vaccinating kids and what it does,” said Dr. David Wohl, the medical director of the vaccine clinic at the University of North Carolina, who is not involved the study.

In a separate study, Moderna is testing its vaccine in 3,000 children ages 12 to 17, and may have results for that age group by summer. The vaccine would then have to be authorized for use in children, so it would not be immediately available.

Many parents want protection for their children, and vaccinating children should help to produce the herd immunity considered crucial to stopping the pandemic. The American Academy of Pediatrics has called for expansion of vaccine trials to include children.

Vaccine side effects like fever, sore arms, fatigue and achy joints and muscles can be more intense in children than in adults, and doctors say it is important for parents to know what to expect after their children are inoculated.

Each child in Moderna’s study will receive two shots, 28 days apart. The study will have two parts. In the first, children aged 2 years to less than 12 may receive two doses of 50 or 100 micrograms each. Those under 2 years may receive two shots of 25, 50 or 100 micrograms.

In each group, the first children inoculated will receive the lowest doses and will be monitored for reactions before later participants are given higher doses.

Then, researchers will perform an interim analysis to determine which dose is safest and most likely to be protective for each age group.

Children in part 2 of the study will receive the doses selected by the analysis — or placebo shots consisting of salt water.

Moderna developed its vaccine in collaboration with the National Institute of Allergy and Infectious Diseases. The company and the institute are also working together on the study, along with the federal Biomedical Advanced Research and Development Authority.

The children will be followed for a year, to look for side effects and measure antibody levels that will help researchers determine whether the vaccine appears to provide protection. The antibody levels will be the main indicator, but the researchers will also look for coronavirus infections, with or without symptoms.

Dr. Wohl said the study appeared well designed and likely to be efficient, but he questioned why the children were to be followed for only one year, when adults in Moderna’s study are followed for two years. He also said he was somewhat surprised to see the vaccine being tested in children so young this soon.

“Should we learn first what happens in the older kids before we go to the really young kids?” Dr. Wohl asked. Most young children do not become very ill from Covid, he said, though some develop a severe inflammatory syndrome that can be life threatening.

Johnson & Johnson has also said it would test its coronavirus vaccine in babies and young children after testing it first in older children.

Pfizer-BioNTech is testing its vaccine in children ages 12 to 15, and has said it plans to move to younger groups; the product is already authorized for use in those 16 and up in the United States.

Last month, AstraZeneca began testing its vaccine in Britain in children 6 years and older.

Weekly Health Quiz: Runner's High, Vaccine Side Effects and Life After Vaccination

1 of 7

These brain chemicals appear to be the main reason that runners experience the euphoria known as “runner’s high”:

Dopamine

Endorphins

Endocannabinoids

Oxytocin

2 of 7

New recommendations from the Centers for Disease Control and Prevention allow adults who have been fully vaccinated against Covid-19 to:

Gather in small groups without social distancing

Allow grandparents to visit unvaccinated grandchildren

Have mask-free dinner parties with vaccinated friends

All of the above

3 of 7

This group is more likely to experience Covid vaccine side effects:

Men

Women

Women and men experience side effects more or less equally

4 of 7

Compared to people of a healthy weight, people who are underweight who develop Covid-19 are:

More likely to be hospitalized

Less likely to be hospitalized

More likely to die

Less likely to die

5 of 7

New guidelines for lung cancer, the leading cause of cancer deaths, advise annual screening starting at age 50 for those who have a smoking history of at least a pack a day for how many years?

10 years

20 years

30 years

Only current smokers should get screened

6 of 7

Symptoms of myasthenia gravis can include which of the following symptoms?

Progressive weakness

Drooping eyelid

Difficulty swallowing

All of the above

7 of 7

Myeloproliferative neoplasms are a type of cancer that affects these blood cells:

Red blood cells

White blood cells

Platelets

All of the above

European Countries Suspend Use of AstraZeneca Shots over Worries About Blood Clots

European Countries Suspend Use of AstraZeneca Shots Over Worries About Blood Clots

Millions of people have received the vaccine without safety problems, and there is no evidence of any causal link between the vaccine and blood clots.

A health authority van arrives at a  school on a remote island in Denmark.
A health authority van arrives at a  school on a remote island in Denmark.Credit…Claus Fisker/Ritzau Scanpix, via Reuters
  • March 11, 2021, 7:11 p.m. ET

Health authorities in three European countries on Thursday suspended use of AstraZeneca’s vaccine because of concerns that it might increase the risk of blood clots, but emphasized that they were taking action as a precaution and that there is no evidence of any causal link.

Denmark acted after a 60-year-old woman who received a shot died after developing a blood clot. Several other European countries had recently stopped using doses from the same batch of the vaccine after some reports of severe blood clots, and European drug regulators are investigating.

In the flurry of suspensions on Thursday, Norway and Iceland followed Denmark’s lead. Italy and Romania also paused shots, but only from a different batch of the vaccine than the one that had raised concerns elsewhere.

Public health experts expect medical conditions to turn up by chance in some people after they get any vaccine, just by chance. In the vast majority of cases such illnesses have nothing to do with the shots. Most other countries where the vaccine has been given to many millions of people have not reported similar red flags.

The safety scare is a setback for AstraZeneca’s vaccine, which has already struggled with a perception that it is a less desirable shot because it had a lower overall efficacy rate in clinical trials than some others. There is, however, extensive data showing that the vaccine is safe and effective, and especially good at preventing severe illness and death. And in many places across the world, it is the only shot available.

As of Wednesday, 30 cases of obstructive blood clots had been reported among nearly five million people vaccinated with the AstraZeneca vaccine in the European Union and three other European countries — a rate no higher than in the general population, the European Medicines Agency said. The agency, Europe’s main drug regulator, said that the vaccine’s benefits outweigh any risks.

The agency also said that there is no indication the vaccine “has caused these conditions.”

Gonzalo Viña, a spokesman for AstraZeneca, said the company’s data have not turned up such safety issues. “An analysis of our safety data of more than 10 million records has shown no evidence of an increased risk of pulmonary embolism or deep vein thrombosis in any defined age group, gender, batch or in any particular country,” he said.

Blood clots, particularly if they are large, can damage tissue or organs like the lungs, heart or brain. Severe cases can be fatal, but people with small clots can often be treated outside of a hospital with prescription drugs.

Daniel Salmon, director of the Institute for Vaccine Safety at Johns Hopkins University, said that authorities noticing the cases and investigating them is a sign of the system working as it should. “I wouldn’t jump to any conclusions that because you saw some blood clots after vaccination that they’re causal,” he said. “It warrants looking at it more carefully.”

Dr. Salmon said he is worried that an unsubstantiated safety scare will cause public panic and deter people from taking a vaccine that is badly needed to end the pandemic.

“There is a possibility for a real problem. There’s a much higher probability that some coincidental event will scare people — and derail the program,” Dr. Salmon said.

AstraZeneca’s vaccine has already faced production lags that caused a slow and bumpy rollout in Europe. What’s more, some people in Germany and other countries have resisted the vaccine, saying they prefer shots that showed higher efficacy in trials.

At the center of the latest scrutiny is a specific batch of one million doses of the vaccine, which was delivered to 17 European Union countries. The European Medicines Agency said a quality defect in that batch was “unlikely” but that the possibility would be investigated further.

Denmark’s drug regulator halted all use of the vaccine for at least 14 days. Health officials have said they wanted to err on the side of safety.

Austria over the weekend suspended use of that same batch after severe blood clots turned up in several people who received those doses. One person died 10 days after vaccination. Another is now recovering after being hospitalized.

Estonia, Lithuania, Luxembourg and Latvia followed Austria’s lead in suspending use of that batch, though they will continue to inoculate their citizens with AstraZeneca doses from other batches.

Italy’s suspension of a different batch was tied to a man in Sicily who died after receiving his shot. It’s unclear whether a blood clot was involved.

More than 142,000 people in Denmark, which has a population of about six million, have been injected with the vaccine produced by AstraZeneca.

The Danish minister of health, Magnus Heunicke, said on Twitter that it is “currently not possible to conclude whether there is a connection.” He added. “We acted early, it needs to be thoroughly investigated.”

Denmark had already scaled back the target for finishing its immunization campaign in part because of delays in deliveries. The safety pause will delay it further.

AstraZeneca’s vaccine came under scrutiny over potential safety issues last year while it was being tested in clinical trials. Two vaccinated volunteers in Britain developed neurological symptoms consistent with transverse myelitis, an inflammatory syndrome that affects the spinal cord and is often caused by viral infections.

Those concerns temporarily shut down global trials of the vaccine, but investigations ultimately found no evidence linking the symptoms to the vaccine. One of the participants who fell ill was later found to have an undiagnosed case of multiple sclerosis.

More than 70 countries have since authorized the vaccine, with the notable exception of the United States, where regulators are waiting on data from a large clinical trial there expected in the next few weeks. A decision from the Food and Drug Administration on whether to authorize AstraZeneca’s vaccine is likely more than a month away.

The most extensive real-world data on the vaccine’s safety comes from Britain, which had administered 9.7 million doses through last month. The British drug regulator, the Medicines and Healthcare Products Regulatory Agency, said “the number and nature of suspected adverse reactions reported so far are not unusual in comparison to other types of routinely used vaccines.”

Rebecca Robbins reported from Bellingham, Wash., and Thomas Erdbrink from Amsterdam. Jason Horowitz and Emma Bubola contributed reporting from Italy, Benjamin Mueller from London and Denise Grady from New York.

Hunting for a Leftover Vaccine? This Site Will Match You With a Clinic.

Hunting for a Leftover Vaccine? This Site Will Match You With a Clinic.

More than half a million people have signed up for Dr. B, a service that promises to match them with clinics struggling to equitably dole out extra doses before they expire.

Allison Ingram, a pharmacist, administered the Moderna Covid vaccine to Thomas Black at Cornerstone Pharmacy - Rodney Parham in Little Rock, Ark., on Monday.
Allison Ingram, a pharmacist, administered the Moderna Covid vaccine to Thomas Black at Cornerstone Pharmacy – Rodney Parham in Little Rock, Ark., on Monday.Credit…Rory Doyle for The New York Times

  • March 9, 2021, 7:00 a.m. ET

In the hustle to score an elusive vaccine appointment, the leftover dose has become the stuff of pandemic lore.

Extra shots — which must be used within hours once taken out of cold storage — have been doled out to drugstore customers buying midnight snacks, people who are friends with nurses and those who show up at closing time at certain grocery stores and pharmacies. At some larger vaccination sites, the race to use every dose sets off a flurry of end-of-the-day phone calls.

In every case, if the leftover dose does not find an available arm, it must go into the trash.

Now, a New York-based start-up is aiming to add some order to the rush for leftover doses. Dr. B, as the company is known, is matching vaccine providers who find themselves with extra vaccines to people who are willing to get one at a moment’s notice.

Since the service began last month, more than 500,000 people have submitted a host of personal information to sign up for the service, which is free to join and is also free to providers. Two vaccine sites have begun testing the program, and the company said about 200 other providers had applied to participate.

Dr. B is just one attempt at coordinating the chaotic patchwork of public and private websites that allow eligible people to find vaccine appointments. Critics have said the current system is confusing, unreliable and often requires access to the internet, as well as the time to prowl websites for the rare appointment. In many places, it also largely ignores people who aren’t yet eligible for a shot, wasting the opportunity to get them on a formal waiting list.

While Dr. B does not solve all of those broader problems, if it scales up the way some hope that it will, it could serve as a model for a better, more equitable way of scheduling vaccinations.

“I think that’s a great idea,” said Sharon Whisenand, the administrator of the Randolph County Health Department in rural Missouri.

Ms. Whisenand said that 60 to 80 people failed to show up to the county’s first mass vaccination event in late January, prompting her staff to make dozens of calls at the end of the day to people on a waiting list. “We sounded a little like a call center for a bit,” she said. The workers eventually found enough takers to administer most of the extra doses, but some shots were thrown out.

Dr. B is a for-profit effort, set up as a public-benefit corporation that includes efficient and equitable vaccine distribution in its mission. But its founder, Cyrus Massoumi, a tech entrepreneur, hasn’t yet described Dr. B’s business model. He said he was financing the project out of his own pocket and had no plans to collect revenue. The company is named after his grandfather, who was nicknamed Dr. Bubba and became a doctor during the 1918 influenza pandemic.

Mr. Massoumi is a founder and former chief executive of ZocDoc, which helps patients find available doctor’s appointments, and the founder of Shadow, a company that reunites lost pets with their owners using technology and local volunteers. Like both of those efforts, Dr. B seeks to make connections between groups that need something from each other.

“Ultimately, patients need this vaccine, and there’s providers who need help getting it to the people of priority,” Mr. Massoumi said in an interview. “That’s my motivation.”

Brittany Marsh, pharmacist and owner of Cornerstone Pharmacy – Rodney Parham, with vials of the Pfizer-BioNTech vaccine.Credit…Rory Doyle for The New York Times
More than 500,000 people have signed up with Dr. B since it began last month, and the company said about 200 vaccine providers had applied to participate.Credit…Rory Doyle for The New York Times

After coming up with the idea for Dr. B in January, Mr. Massoumi recruited several engineers from Haven, a now-defunct health care collaboration among Amazon, Berkshire Hathaway and J.P. Morgan, to build its website and underlying database. Amazon also donated web services, Mr. Massoumi said.

The half a million people who have signed up for the service entered basic biographical information, such as their date of birth, address, underlying health conditions and the type of work they do. If vaccine providers near them have extra doses, they will get notified via text message and have 15 minutes to respond. Then they must be willing to quickly travel to the vaccination site.

The company’s database sorts people by local rules about vaccine priority, giving providers better odds of administering their leftover shots to those in the greatest need.

For many providers, that orderly procedure would be a welcome change from the haphazard systems they are using now. At some pharmacies and supermarket chains, workers have resorted to combing the shopping aisles to find people willing to get a last-minute vaccine. At other locations, vaccine hopefuls wait in line at the end of every shift, which could pose an infection risk, particularly to the most vulnerable.

Despite some grumbling about younger, healthier people skipping the line by snapping up leftover doses, public health experts and many ethicists say the most important thing is that the vaccines don’t go to waste. Earlier in the vaccine rollout, some politicians, such as Gov. Andrew M. Cuomo of New York, threatened sanctions against providers for not precisely following priority rules, and a doctor in Texas lost his job after he gave expiring doses to people with medical conditions, including his wife.

Vaccines ready to be administered at Cornerstone Pharmacy - Rodney Parham.
Vaccines ready to be administered at Cornerstone Pharmacy – Rodney Parham.Credit…Rory Doyle for The New York Times
Ms. Marsh said that the pharmacy had been testing the Dr. B service for a few weeks.Credit…Rory Doyle for The New York Times

For those who are offered a last-minute vaccine, “that person should not say no because they want it to go to someone else,” said Dr. Shikha Jain, an assistant professor of medicine at the University of Illinois Chicago, and a co-founder of IMPACT, a group that has been working to improve the equitable distribution of vaccines. However, “it’s really important to be intentional and to be equitable,” she said.

Mr. Massoumi said he had taken several steps to ensure that the service will be equitable. That has included turning down early media requests from mainstream publications and instead promoting Dr. B on Zoom calls with representatives for groups like Black churches and Native American community groups, given that the pandemic has disproportionately affected nonwhite groups.

“It was really important for him to let these communities have potentially a place at the front of the line, or to get the information early,” said Brooke Williams, who is Black and a member of the Resistance Revival Chorus in New York. She joined one of the early Zoom calls and began spreading the word.

“Hearing about shots that were getting thrown out was just heartbreaking and infuriating,” she said.

The service suffers, however, from some of the same barriers that have marred vaccination efforts so far. Although signing up is simple, doing so requires an internet connection as well as ready access to a cellphone. Because of the last-minute nature of leftover doses, participants must have flexible schedules and access to transportation.

“It’s still heavily internet dependent, so it will depend on who hears about it,” said Arthur Caplan, a medical ethicist at New York University’s Grossman School of Medicine. “It seems he’s trying to solve a problem and do some good, but I’m sad that governments — counties, cities, national organizations — didn’t prepare for this and then didn’t react more quickly to give advice and guidance.”

Volunteers registered patients for vaccines at Cornerstone Pharmacy – Rodney Parham.Credit…Rory Doyle for The New York Times
Daron Nelson got his shot at Cornerstone. Dr. B has said that providers in 30 states have shown interest in the platform, from doctors’ offices and pharmacies to medical departments at large academic institutions.Credit…Rory Doyle for The New York Times

Mr. Massoumi noted that the site allowed for people such as community volunteers to sign up on others’ behalf. The site is also available in Spanish.

He noted that the program’s setup, which allows people to sign up, then wait for a notification based on priority, is better than other sites that require hours of refreshing websites in the odds they may luck into a rare opening.

Some local health authorities, including Washington, D.C., and West Virginia, are shifting to a similar preregistration system, which can help to level the playing field.

“There is this feeling where you don’t know where you stand, and the only way to secure your place is by refreshing a browser,” said John Brownstein, a Boston Children’s Hospital researcher who runs VaccineFinder.org, an online portal that helps people book vaccine appointments.

For Brittany Marsh, who owns a pharmacy in Little Rock, Ark., figuring out what to do with leftover doses was a daily headache.

She said the number of no-shows had increased as vaccines have become more available, and others have had to cancel at the last minute because they developed Covid-19 or were exposed to someone who did. Although sometimes people do call, she said, “more times than not, we just have a no-show.”

Ms. Marsh has been testing Dr. B’s service for a few weeks and said it saved her workers the hassle of calling a waiting list of other customers to quickly fill the open slots. With Dr. B, she said, “I know that they’re calling at least what we think is the right group of people to come get those shots, so that we don’t have to ever waste any.”

Dr. B has revealed few details about which providers have expressed interest in using its platform, other than to say the providers are based in 30 states and include doctors’ offices, pharmacies and the medical departments at large academic institutions.

The company collects sensitive personal information that it vows to closely safeguard, even though, because the company is not itself a medical provider, the data is not protected by the federal health care privacy law known as HIPAA.

When asked about his long-term plans for the company, Mr. Massoumi demurred, noting that the race to vaccinate was not going to end anytime soon.

“Right now, we just want to get the vaccines allocated in the best possible way,” he said. “I can’t think of a better use of money to help solve the pandemic, so we’re just heads down, focused on that.”