Federal regulators Thursday authorized booster shots of Pfizer-BioNTech's coronavirus vaccine for 16- and 17-year-olds, a step that officials said would bolster protection against delta, the variant behind surging infections in parts of the United States, and could help tame the emerging omicron version.
The Food and Drug Administration's decision came the day after new data from the companies suggested that boosters may play a critical role in helping to control the omicron variant by raising virus-fighting antibodies to block the pathogen, which echoed a finding by leading scientists in South Africa released earlier this week.
Rochelle Walensky, director of the Centers for Disease Control and Prevention, endorsed the FDA move, citing the early data indicating that boosters strengthen the body's defenses against the virus. She encouraged everyone 16 and 17 years old who has been vaccinated to get a booster -- as soon as they are six months past their second shot.
The Pfizer vaccine is the only option in the U.S. for anyone younger than 18, either for initial vaccination or for use as a booster. It's not yet clear if or when teens younger than 16 might need a third Pfizer dose. But Walensky said the CDC and FDA would closely watch data on 12- to 15-year-olds because, if they eventually need boosters, "we again will want to act swiftly."
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The Moderna and Johnson & Johnson vaccines are not authorized for anyone under 18. All adults 18 and over have been eligible for boosters for several weeks.
New evidence indicates vaccine effectiveness is waning for adults and for those in the 16- and 17-year-old age group, Peter Marks, the FDA's top vaccine regulator, said in a statement. A booster "will help provide continued protection," he said.
About 200 million Americans are fully vaccinated, including about 4.7 million 16- and 17-year-olds, many of whom got their first shots in the spring and would be eligible for a booster.
"Vaccination and getting a booster when eligible, along with other preventive measures like masking and avoiding large crowds and poorly ventilated spaces, remain our most effective methods for fighting covid-19," Dr. Janet Woodcock, acting FDA commissioner, said in a statement.
The FDA said its authorization was based on data it had previously analyzed in examining extra doses for adults 18 and older.
The agency also said it had concluded that the benefits of a booster outweigh the risks of rare cardiac side effects, including the swelling of heart muscle, in 16- and 17-year-olds. That condition, called myocarditis, has been linked to the Pfizer-BioNTech and Moderna vaccines, occurring in male adolescents and young men.
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Health officials in Israel, which already gives boosters to teens, have said the side effect continues to be rare with third doses.
A U.S. study this week offered additional reassurance. Researchers from children's hospitals around the country checked medical records and found the rare side effect usually is mild and people recover quickly. The research was published Monday in the journal Circulation.
The expanded age for Pfizer-BioNTech boosters is sure to raise questions among parents and doctors about whether -- and when -- children younger than 16 will need boosters.
QUESTIONS TO ANSWER
Scientists inside and outside of the government said more information is needed before a decision is made about boosters for younger children. Some experts believe those children eventually will need boosters, but perhaps can wait more than six months after their second shot.
"They probably will need boosts," said one federal official who spoke on the condition of anonymity because he was not authorized to discuss the issue. "The question is: Will they need boosts at six months or could they last longer?"
Pfizer and its partner, BioNTech, have not asked the FDA for the go-ahead for boosters for younger children, according to Kit Longley, a Pfizer spokesman.
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"We will continue to monitor data from our ongoing clinical trial in addition to real world evidence to assess a potential need," Longley said.
Octavio Ramilo, chief of infectious diseases at Nationwide Children's Hospital in Columbus, Ohio, praised the authorization for 16- and 17-year-olds.
"These are the kids who go out, they have very active social lives," Ramilo said. "So it's very important that we protect them and the community."
Kenneth Alexander, chief of infectious diseases at Nemours Children's Hospital in Orlando, agreed, saying the emergence of variants, including delta and omicron, underscored the importance of broadening access to boosters.
"A vaccine is to your immune system like an FBI most-wanted poster in the post office," Alexander said. "If I show it once, you remember the person's face. Twice, you really remember. And three times, you can pick that person out of the crowd."
Not everyone agrees young people need boosters.
Paul A. Offit, director of the Vaccine Education Center at the Children's Hospital of Philadelphia, said on a media call Wednesday that he didn't see a "compelling reason" to administer a booster to healthy young people. The two-dose regimen adequately protects those individuals from serious illness, he said.
Young people generally have stronger immune systems than older people. If they get sick with covid, they are less likely to become seriously ill.
The Pfizer-BioNTech two-shot vaccine was approved in August for anyone 16 and older. It was authorized in October on an emergency basis for children between 5 and 15.
Pfizer is testing the vaccine in children under 5, with data expected late this year or early next year. The vaccine could be available to the youngest children in the first part of 2022, company officials have said.
Not all parents are clamoring for vaccines and boosters for their teenagers and younger children, however.
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HESITANT PARENTS
A Kaiser Family Foundation survey released Thursday found that demand for vaccines, after a strong start, has slowed for the 12- to 17-year-old group. About half of parents said their teens had received at least one dose as of November, essentially unchanged from two months earlier, the survey showed.
Parents of children 5- to 11-years-old, who became eligible for vaccinations more recently, were even less enthusiastic. Sixteen percent said their younger children have received at least one vaccine dose and another 13% said they plan to get them vaccinated "right away," the survey showed.
Three in 10 parents of teens and younger children said they will "definitely not" get their child vaccinated, according to the survey, which was conducted before news of the omicron variant emerged. But interest in boosters for all age groups may rise if the early data holds up that shows boosters are a way to shield people from omicron-induced infections and serious illness.
Some leading experts, such as Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, are increasingly referring to the mRNA vaccines -- the Pfizer-BioNTech and Moderna shots -- as three-dose regimens.
"The booster shot could be the answer to the challenge that we're facing with the omicron," Fauci said Wednesday at a Washington Post Live event. But he noted that the data was preliminary.
Albert Bourla, chairman and chief executive of Pfizer, called the FDA action a "critical milestone" in helping stem the spread of covid and the omicron variant.
Pfizer and BioNTech in October said a later-stage trial showed a booster dose given to individuals 16 and older demonstrated it was more than 95% effective when compared with those who did not receive a booster.
Vaccine makers are racing to update their covid-19 shots against the newest coronavirus threat even before it's clear a change is needed, just in case.
KEEPING UP WITH COVID
Experts doubt today's shots will become useless but say it's critical to see how fast companies could produce a reformulated dose and prove it works -- because whatever happens with omicron, this newest mutant won't be the last.
Omicron "is pulling the fire alarm. Whether it turns out to be a false alarm, it would be really good to know if we can actually do this -- get a new vaccine rolled out and be ready," said immunologist E. John Wherry of the University of Pennsylvania.
Better answers are expected in the coming weeks and regulators in the U.S. and other countries are keeping a close watch. The World Health Organization has appointed an independent scientific panel to advise on whether the shots need reformulating because of omicron or any other mutant.
But authorities haven't laid out what would trigger such a drastic step: If vaccine immunity against serious illness drops, or if a new mutant merely spreads faster?
"This is not trivial," BioNTech CEO Ugur Sahin said shortly before omicron's discovery. A company could apply to market a new formula "but what happens if another company makes another proposal with another variant? We don't have an agreed strategy."
It's a tough decision -- and the virus moves faster than science. Just this fall the U.S. government's vaccine advisers wondered why boosters weren't retooled to target the extra-contagious delta variant -- only to have the next scary mutant, omicron, be neither a delta descendant nor a very close cousin.
The extra-contagious delta variant is causing nearly all covid-19 infections in the U.S., and in much of the world.
It's not yet clear how vaccines will hold up against the new and markedly different omicron mutant. But there's strong evidence that boosters offer a jump in protection against delta-caused infections, currently the biggest threat.
Covid-19 vaccines work by triggering production of antibodies that recognize and attack the spike protein that coats the coronavirus, and many are made with new technology flexible enough for easy updating. The Pfizer and Moderna vaccines are fastest to tweak, made with genetic instructions that tell the body to make harmless copies of the spike protein -- and that messenger RNA can be swapped to match new mutations.
Pfizer expects to have an omicron-specific candidate ready for the FDA to consider in March, with some initial batches ready to ship around the same time, chief scientific officer Dr. Mikael Dolsten told The Associated Press.
Moderna is predicting 60 to 90 days to have an omicron-specific candidate ready for testing. Other manufacturers that make covid-19 vaccines using different technology, including Johnson & Johnson, also are pursuing possible updates.
Pfizer and Moderna already have successfully brewed experimental doses to match delta and another variant named beta, shots that haven't been needed but offered valuable practice.
So far, the original vaccines have offered at least some cross-protection against prior variants. Even if immunity against omicron isn't as good, Fauci hopes the big antibody jump triggered by booster doses will compensate.
Pfizer's preliminary lab testing, released Wednesday, hint that might be the case but antibodies aren't the only layer of defense. Vaccines also spur T cells that can prevent serious illness if someone does get infected, and Pfizer's first tests showed, as expected, those don't seem to be affected by omicron.
Also, memory cells that can create new and somewhat different antibodies form with each dose.
"You're really training your immune system not just to deal better with existing variants, but it actually prepares a broader repertoire to deal with new variants," Dolsten said.
How aggressive a mutant is also plays a role in whether to reformulate the vaccine. Omicron appears to spread easily but early reports from South African scientists hint that it might cause milder infections than previous variants.
Flu vaccines protect against three or four different strains of influenza in one shot. If a vaccine tweak is needed for omicron, authorities will have to decide to whether to make a separate omicron booster or add it to the original vaccine -- or maybe even follow the flu model and try another combination.
There's some evidence that a covid-19 combo shot could work. In a small Moderna study, a so-called bivalent booster containing the original vaccine and a beta-specific dose caused a bigger antibody jump than either an original Moderna booster or its experimental beta-specific shot.
Information for this article was contributed by Laurie McGinley and Lena H. Sun of The Washington Post and by Lauran Neergaard, Mike Stobbe, Matthew Perrone and Jamey Keaten of The Associated Press.