The Food and Drug Administration cleared the first coronavirus vaccine for emergency use in children as young as 12 on Monday, expanding access to the Pfizer-BioNTech shot to adolescents ahead of the next school year and marking another milestone in the nation’s battle with the virus.
The decision that the two-shot regimen is safe and effective for younger adolescents had been highly anticipated by many parents and pediatricians, particularly with the growing gap between what vaccinated and unvaccinated people may do safely. Evidence suggests that schools can function at low risk with prevention measures, such as masks and social distancing. But vaccines are poised to increase confidence in resuming in-person activities and are regarded as pivotal to returning to normalcy.
“Adolescents, especially, have suffered tremendously from the covid pandemic. Even though they’re less likely than adults to be hospitalized or have severe illness, their lives really have been curtailed in many parts of the country,” said Kawsar R. Talaat, an assistant professor of international health at the Johns Hopkins Bloomberg School of Public Health. “A vaccine gives them an extra layer of protection and allows them to go back to being kids.”
Expert advisers to the Centers for Disease Control and Prevention are scheduled to meet Wednesday to recommend how the vaccine should be used in that age group, and the vaccine can be administered as soon as the CDC director signs off on the recommendation.
In a news briefing Monday evening after the announcement, FDA officials said the Pfizer authorization for 12- to 15-year-olds was a straightforward decision because the data showed that the vaccine was safe and that the response to the vaccine was even better than among the 18- to 25-year-olds who got the shots.
Children rarely suffer serious bouts of covid-19, the illness caused by the coronavirus. But there is no way to predict the few who will become dangerously sick or develop a rare, dangerous inflammatory syndrome. Out of more than 581,000 covid-19 deaths in the United States, about 300 have been people under 18 — a tiny fraction of the total. But that exceeds the number of children who die in a bad flu season.
Children appear to be less efficient at spreading the virus, although their role in transmission is still not fully understood — another reason for pediatric vaccinations.
Clinicians also worry that with a new virus with many unknowns, the possibility exists for long-term impacts of infection, even from the mild or asymptomatic courses of illness common among children.
The Pfizer-BioNTech vaccine, already authorized for adolescents 16 and older, was the first to be tested in younger adolescents. The FDA’s decision will provide a potential path for other vaccine-makers to follow, most of which have launched or plan to initiate trials of their vaccines in teenagers and younger children.
The agency based its authorization on a trial of nearly 2,300 adolescents between 12 and 15 years old, half of whom received the same two-shot regimen shown effective and safe in adults. Researchers took blood samples and measured antibody levels triggered by the shots and foundstronger immune responses in the teens than those found in young adults. There were 16 cases of covid-19 in the trial, all of them among adolescents who received a placebo, suggesting the regimen offered similar protection to younger recipients as it does to adults.
Robert W. Frenck Jr., the researcher who led the adolescent trial at Cincinnati Children’s Hospital Medical Center, said the study was designed to test whether it triggered immune responses, not whether it prevented disease. But because of the number of children who became ill in the placebo arm of the trial, it also became evident the vaccine offered robust protection.
“That really points out how much covid there is in the adolescent community,” Frenck said.
The data has not been published or peer-reviewed, but Kathryn M. Edwards, a pediatric infectious-disease specialist at Vanderbilt University Medical Center, said the results announced by Pfizer were “pretty exciting — it looked very effective and the immune responses were really good.”
Edwards said she is comfortable the benefits of vaccinations are clear among teens, noting that while children, in general, are at lower risk of severe covid-19 than adults, older adolescents seem to be more like adults in their risk for covid-19 than the very youngest children.
Audrey Baker, 15, and Sam Baker, 12, rolled up their sleeves for shots in the Pfizer-BioNTech trial at Cincinnati Children’s Hospital Medical Center. Audrey said she had no hesitation about signing up, and misses little things about how life used to be — eating out in restaurants and seeing family.
“I just trusted the science,” Audrey said. “I knew it was tested in adults. I was really just joining, hoping that maybe I could get vaccinated and help out science.”
Sam said he was more hesitant, in part because participating meant many follow-up lab tests. But he decided to do it and thinks he may have gotten the vaccine in the trial because he developed a headache and fever after his second dose.
Their mother, Rachel Baker, said she felt relief because of Sam’s symptoms.
“The biggest benefit has been that I feel a weight off my shoulders,” Rachel said. “We haven’t changed how we do anything. … We’re still masking, we’re still social distancing, but we’re a bit calmer about it all.”
H. Cody Meissner, a pediatrician at Tufts Medical Center and a member of an external advisory committee to the FDA, said he thinks a pediatric vaccine is needed. But he said he would like to see more safety data because the messenger RNA technology at the core of vaccines from Pfizer-BioNTech and the biotechnology company Moderna does not have a long, established safety record, and its first large-scale use began in December.
Meissner abstained from the December vote that overwhelmingly recommended authorization of the Pfizer-BioNTech vaccine for people 16 and older, because he thought the vaccine should be authorized in people 18 and older.
“For those who are eager to get it, it’s important for them to understand that this is very rarely a severe disease in young adolescents, number one, and this is an entirely new vaccine,” Meissner said. “I just don’t want people to get too swept up in fear of hospitalization and death from covid-19 for the first few decades of life.”
But many other physicians take comfort knowing that 250 million shots of messenger RNA vaccine have been given in the United States alone. Serious side effects, such as a risk of anaphylaxis, are extremely rare. Because the trial in teens was an “immune bridging” trial designed to test whether the vaccine triggered immune responses similar to those in adults, researchers did not need to recruit tens of thousands of people to see if those who received a vaccine were protected against illness. The immune bridging technique is commonly used to expand access to vaccines that have been proved effective and safe to adolescents or other populations.
The expansion of eligibility to children will probably ignite debates in families about when to get vaccinated, and among policymakers about whether it should be required.
Dorit Reiss, a law professor focused on vaccine policy at the University of California Hastings College of Law, said she thinks it is unlikely children will be mandated to receive a coronavirus shot until the vaccines win full approval and not just emergency use authorization.
She predicted that acceptance of the vaccine will evolve as more children are vaccinated and depend on the state of the pandemic. She noted that when vaccines are introduced, the rollout often starts slowly before accelerating.
“Nervousness about a new vaccine is normal, especially when it’s for kids,” Reiss said. “Parents that are nervous now might feel different in a few months, once their friends’ kids have gotten vaccinated. And the views of the kids are also going to matter — if teens are going to think this is going to make their lives easier.”
Opening up vaccinations to children may sharpen a debate unfolding globally about the equity of vaccine access. Talaat said that while she can’t wait for her kids to have access to a vaccine, she is troubled by the global inequities as high-risk front-line workers or older people still don’t have access to vaccines in countries where the coronavirus is out of control.
Moderna announced Thursday that an initial analysis of its teen trial found its vaccine was 96 percent effective among participants who received at least one dose. Moderna is in discussions with regulators about the data. Pfizer-BioNTech and Moderna are testing their vaccines in children as young as infants. Johnson & Johnson is planning pediatric trials of its single-shot vaccine.
Trials in younger children are expected to take longer, because researchers must step down gradually in age and determine a safe and effective dose. William Gruber, senior vice president of vaccine clinical research and development at Pfizer, said data from tests in children as young as 2 years old may be available by September or October, with data on children as young as 6 months possible by the end of the year.
Within each age category, a separate risk-benefit assessment may take place. In the youngest children, given the low risk from the coronavirus, side effects may figure more prominently into the analysis, for example. Researchers may end up choosing a lower dose of vaccine. The understanding of children’s role in transmission may also evolve and help guide vaccine use and public policy.
“We are proceeding carefully, cautiously,” Edwards said. “We’re using the same rigid guidelines we use in all vaccines, and we take this very seriously. I think as time goes on and more information becomes available, some of the questions may be easier to address.”
“A vaccinated friend attended an indoor gathering of 35 people, half of which were unvaccinated. Nobody wore masks or socially distanced. I am vaccinated, but should I avoid contact with this person for some period of time? I am concerned that my friend may have inadvertently been exposed to variants, although no problems as of three days post-event.”
The scenario you describe is likely to be low risk to you and your friend because you’re both vaccinated. It’s not ideal — mostly from the perspective of the people at the meet-up who weren’t vaccinated yet. When non-immunized and immunized people gather in a space, precautions should account for those who haven’t had their shots yet, the Centers for Disease Control and Prevention advises. Those precautions include everyone wearing masks inside in public or indoors if there’s a multi-household mix of people who aren’t vaccinated.
Mingling indoors without masks or distancing is “likely low risk for the vaccinated people,” the CDC writes (the emphasis is the agency’s). That’s because the vaccines are so protective.
Real-world results continue to support clinical trial conclusions that coronavirus vaccines are highly effective at preventing symptomatic covid-19. In a CDC study of almost 2,500 fully vaccinated health-care workers, only three had confirmed infections. “Front-line workers were 90 percent less likely to be infected with the virus that causes covid-19,” an epidemiologist and author of that study told The Post last month.
Emerging reports also suggest vaccines hinder asymptomatic infection. Two doses of an mRNA vaccine reduced that by 92 percent in Israel, according to a study published this week in The Lancet. And there’s encouraging news that vaccines protect against variants of concern. As we mentioned above, and reported Wednesday, research in the New England Journal of Medicine showed the Pfizer-BioNTech vaccine was “90 percent effective at blocking infections caused by the B.1.1.7 variant,” which is the more transmissible variant first detected in the U.K. The vaccine was slightly less effective, at 75 percent, against the B.1.351 variant identified in South Africa.
It’s good to hear that there haven’t been any problems in the days after this gathering. From what you’ve described, it doesn’t sound as though your friend needs to take any actions like quarantining. In fact, the CDC advises quarantine is generally unnecessary for fully vaccinated people, even after known exposure, unless an immunized person begins to show symptoms.
That said, you’ve asked journalists, not doctors — here’s our usual disclaimer to consult your primary-care physician if you have specific concerns about your susceptibility to the virus. If you’re wary about jumping back into social life, that’s okay, too, and not unusual after living through an ongoing pandemic. Some psychologists suggest easing into social situations post-vaccination, borrowing from principles of exposure therapy; for instance, if you’re anxious and would like to take extra precautions for your next visit with your friend, you might suggest meeting up while outside or you can wear a mask.
Widely circulating coronavirus variants and persistent hesitancy about vaccines will keep the goal out of reach. The virus is here to stay, but vaccinating the most vulnerable may be enough to restore normalcy.
Early in the pandemic, when vaccines for the coronavirus were still just a glimmer on the horizon, the term “herd immunity” came to signify the endgame: the point when enough Americans would be protected from the virus so we could be rid of the pathogen and reclaim our lives.
Now, more than half of adults in the United States have been inoculated with at least one dose of a vaccine. But daily vaccination rates are slipping, and there is widespread consensus among scientists and public health experts that the herd immunity threshold is not attainable — at least not in the foreseeable future, and perhaps not ever.
Instead, they are coming to the conclusion that rather than making a long-promised exit, the virus will most likely become a manageable threat that will continue to circulate in the United States for years to come, still causing hospitalizations and deaths but in much smaller numbers.
How much smaller is uncertain and depends in part on how much of the nation, and the world, becomes vaccinated and how the coronavirus evolves. It is already clear, however, that the virus is changing too quickly, new variants are spreading too easily and vaccination is proceeding too slowly for herd immunity to be within reach anytime soon.
Continued immunizations, especially for people at highest risk because of age, exposure or health status, will be crucial to limiting the severity of outbreaks, if not their frequency, experts believe.
“The virus is unlikely to go away,” said Rustom Antia, an evolutionary biologist at Emory University in Atlanta. “But we want to do all we can to check that it’s likely to become a mild infection.”
The shift in outlook presents a new challenge for public health authorities. The drive for herd immunity — by the summer, some experts once thought possible — captured the imagination of large segments of the public. To say the goal will not be attained adds another “why bother” to the list of reasons that vaccine skeptics use to avoid being inoculated.
Yet vaccinations remain the key to transforming the virus into a controllable threat, experts said.
Dr. Anthony S. Fauci, the Biden administration’s top adviser on Covid-19, acknowledged the shift in experts’ thinking.
“People were getting confused and thinking you’re never going to get the infections down until you reach this mystical level of herd immunity, whatever that number is,” he said.
“That’s why we stopped using herd immunity in the classic sense,” he added. “I’m saying: Forget that for a second. You vaccinate enough people, the infections are going to go down.”
Why reaching the threshold is tough
Once the novel coronavirus began to spread across the globe in early 2020, it became increasingly clear that the only way out of the pandemic would be for so many people to gain immunity — whether through natural infection or vaccination — that the virus would run out of people to infect. The concept of reaching herd immunity became the implicit goal in many countries, including the United States.
Early on, the target herd immunity threshold was estimated to be about 60 to 70 percent of the population. Most experts, including Dr. Fauci, expected that the United States would be able to reach it once vaccines were available.
But as vaccines were developed and distribution ramped up through the winter and into the spring, estimates of the threshold began to rise. That is because the initial calculations were based on the contagiousness of the original version of the virus. The predominant variant now circulating in the United States, called B.1.1.7 and first identified in Britain, is about 60 percent more transmissible.
As a result, experts now calculate the herd immunity threshold to be at least 80 percent. If even more contagious variants develop, or if scientists find that immunized people can still transmit the virus, the calculation will have to be revised upward again.
Polls show that about 30 percent of the U.S. population is still reluctant to be vaccinated. That number is expected to improve but probably not enough. “It is theoretically possible that we could get to about 90 percent vaccination coverage, but not super likely, I would say,” said Marc Lipsitch, an epidemiologist at the Harvard T.H. Chan School of Public Health.
Though resistance to the vaccines is a main reason the United States is unlikely to reach herd immunity, it is not the only one.
Herd immunity is often described as a national target. But that is a hazy concept in a country this large.
“Disease transmission is local,” Dr. Lipsitch noted.
“If the coverage is 95 percent in the United States as a whole, but 70 percent in some small town, the virus doesn’t care,” he explained. “It will make its way around the small town.”
Uneven Willingness to Get Vaccinated Could Affect Herd Immunity
In some parts of the United States, inoculation rates may not reach the threshold needed to prevent the coronavirus from spreading easily.
How insulated a particular region is from the coronavirus depends on a dizzying array of factors.
Herd immunity can fluctuate with “population crowding, human behavior, sanitation and all sorts of other things,” said Dr. David M. Morens, a virologist and senior adviser to Dr. Fauci. “The herd immunity for a wealthy neighborhood might be X, then you go into a crowded neighborhood one block away and it’s 10X.”
Given the degree of movement among regions, a small virus wave in a region with a low vaccination level can easily spill over into an area where a majority of the population is protected.
At the same time, the connectivity between countries, particularly as travel restrictions ease, emphasizes the urgency of protecting not just Americans but everyone in the world, said Natalie E. Dean, a biostatistician at the University of Florida in Gainesville. Any variants that arise in the world will eventually reach the United States, she noted.
Many parts of the world lag far behind the United States on vaccinations. Less than 2 percent of the people in India have been fully vaccinated, for example, and less than 1 percent in South Africa, according to data compiled by The New York Times.
“We will not achieve herd immunity as a country or a state or even as a city until we have enough immunity in the population as a whole,” said Lauren Ancel Meyers, the director of the Covid-19 Modeling Consortium at the University of Texas at Austin.
What the future may hold
If the herd immunity threshold is not attainable, what matters most is the rate of hospitalizations and deaths after pandemic restrictions are relaxed, experts believe.
By focusing on vaccinating the most vulnerable, the United States has already brought those numbers down sharply. If the vaccination levels of that group continue to rise, the expectation is that over time the coronavirus may become seasonal, like the flu, and affect mostly the young and healthy.
“What we want to do at the very least is get to a point where we have just really sporadic little flare-ups,” said Carl Bergstrom, an evolutionary biologist at the University of Washington in Seattle. “That would be a very sensible target in this country where we have an excellent vaccine and the ability to deliver it.”
Over the long term — a generation or two — the goal is to transition the new coronavirus to become more like its cousins that cause common colds. That would mean the first infection is early in childhood, and subsequent infections are mild because of partial protection, even if immunity wanes.
Some unknown proportion of people with mild cases may go on to experience debilitating symptoms for weeks or months — a syndrome called “long Covid” — but they are unlikely to overwhelm the health care system.
“The vast majority of the mortality and of the stress on the health care system comes from people with a few particular conditions, and especially people who are over 60,” Dr. Lipsitch said. “If we can protect those people against severe illness and death, then we will have turned Covid from a society disrupter to a regular infectious disease.”
If communities maintain vigilant testing and tracking, it may be possible to bring the number of new cases so low that health officials can identify any new introduction of the virus and immediately stifle a potential outbreak, said Bary Pradelski, an economist at the National Center for Scientific Research in Grenoble, France. He and his colleagues described this strategy in a paper published on Thursday in the scientific journal The Lancet.
“Eradication is, I think, impossible at this stage,” Dr. Pradelski said. “But you want local elimination.”
Vaccination is still the key
The endpoint has changed, but the most pressing challenge remains the same: persuading as many people as possible to get the shot.
Reaching a high level of immunity in the population “is not like winning a race,” Dr. Lipsitch said. “You have to then feed it. You have to keep vaccinating to stay above that threshold.”
Skepticism about the vaccines among many Americans and lack of access in some groups — homeless populations, migrant workers or some communities of color — make it a challenge to achieve that goal. Vaccine mandates would only make that stance worse, some experts believe.
A better approach would be for a trusted figure to address the root cause of the hesitancy — fear, mistrust, misconceptions, ease of access or a desire for more information, said Mary Politi, an expert in health decision making and health communication at Washington University in St. Louis.
People often need to see others in their social circle embracing something before they are willing to try it, Dr. Politi said. Emphasizing the benefits of vaccination to their lives, like seeing a family member or sending their children to school, might be more motivating than the nebulous idea of herd immunity.
“That would resonate with people more than this somewhat elusive concept that experts are still trying to figure out,” she added.
Though children spread the virus less efficiently than adults do, the experts all agreed that vaccinating children would also be important for keeping the number of Covid cases low. In the long term, the public health system will also need to account for babies, and for children and adults who age into a group with higher risk.
Unnerving scenarios remain on the path to this long-term vision.
Over time, if not enough people are protected, highly contagious variants may develop that can break through vaccine protection, land people in the hospital and put them at risk of death.
“That’s the nightmare scenario,” said Jeffrey Shaman, an epidemiologist at Columbia University.
How frequent and how severe those breakthrough infections are have the potential to determine whether the United States can keep hospitalizations and deaths low or if the country will find itself in a “mad scramble” every couple of years, he said.
“I think we’re going to be looking over our shoulders — or at least public health officials and infectious disease epidemiologists are going to be looking over their shoulders going: ‘All right, the variants out there — what are they doing? What are they capable of?” he said. “Maybe the general public can go back to not worrying about it so much, but we will have to.”