A federal advisory committee will decide Friday whether third shots of COVID-19 vaccines are safe and protective against infections.
At root is whether the extra shots are “luxuries” or an essential part of providing complete protection against the virus, presidential adviser Dr. Anthony Fauci said this week.
He and other federal officials, including President Joe Biden, believe it is time to begin offering third shots to compensate for what appears to be fading protection. The government has agreements to purchase the doses and provide them at no cost to consumers.
Others, particularly the director general of the World Health Organization, argue that Americans would benefit far more by getting initial shots to the unvaccinated around the world.
The Food and Drug Administration advisory committee will consider information from Pfizer and its German partner BioNTech in deciding whether to allow the companies to provide third vaccine doses to people 16 and older.
In a rare open letter on the eve of an FDA committee meeting, CEO Albert Bourla said both lab data and real-world evidence from Israel showed boosters can play an important role in addressing the pandemic.
“A booster of the same dose and the same vaccine can achieve this marked enhancement of protection,” Bourla wrote in the letter, published on Pfizer’s website Thursday morning.
FDA officials, however, appeared skeptical about the need for third shots for everyone at this point.
In briefing information provided to the committee and posted online Wednesday, the FDA emphasized studies supporting the need for boosters are not conclusive and were not conducted in the United States, which may see different results than other countries.
“Overall, data indicate that currently US-licensed or authorized COVID-19 vaccines still afford protection against severe COVID-19 disease and death in the United States,” the FDA report concluded.
In the United States, “still well over 90% of people” who are hospitalized with COVID-19 have not been vaccinated, though vaccinated people have begun to catch milder forms of the disease, CDC Director Dr. Rochelle Walensky said in a White House briefing last week.
It’s not clear whether the committee members, all experts in aspects of vaccine development and immunology, will support these booster doses six months after initial doses.
Even if they do decide that third doses are safe and effective, it will be up to the Centers for Disease Control and Prevention and its own advisory committee – scheduled to meet Wednesday and Thursday – to decide who should receive the boosters and on what schedule.
The agencies are considering only the Pfizer-BioNTech vaccine at the moment, which is the only fully approved shot, though they are expected to soon review the Moderna vaccine as well.
Fauci, speaking to a class of undergraduates Wednesday morning at the Massachusetts Institute of Technology, said he thinks it will turn out that people need three doses of the Moderna or Pfizer-BioNTech vaccines in order to get adequate long-term protection against COVID-19. Other diseases, such as hepatitis B, also require a three-dose vaccine regimen for full protection.
“We started with two doses because we needed to get the vaccine out there quickly to save millions of lives, which it already has done,” he told the students. “But when we ultimately get down to looking at this, as the dust settles, it is my opinion and now many of my colleagues’ that the proper complete regimen would be a three-dose regimen as opposed to a two-dose regimen.”
Data from Israel, which Fauci cited, suggests that vaccine protection begins to fade over time, beginning at around six months, with vaccinated people becoming first more prone to mild disease, and then to increasingly severe disease.
Israel, where most people received the Pfizer-BioNTech shots, was one of the first countries to launch wide-scale vaccination against COVID-19 and so has some of the best data about how well those vaccines are holding up over time.
Israeli public health officials are expected to attend Friday’s meeting of the Vaccines and Related Biological Products Advisory Committee to explain their findings in detail.
Other public health and vaccine experts are less persuaded by the available data.
“I’m convinced that protection against symptomatic infection wanes,” said Dr. Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia. But he’s “less convinced about waning of protection against severe disease.”
The purpose of vaccines is not to prevent every single symptom of infection, but to protect people against the most severe outcomes, said Dr. Anna Durbin, who studies experimental vaccines at the Johns Hopkins Bloomberg School of Public Health in Baltimore.
“Right now,” she said on a Wednesday call with media, “the indication is that we don’t need an additional booster.”
There’s no doubt that boosters are effective. “Will it improve your immune response? Will we see higher titers of antibody? Yes. Do the safety data look good? Yes. Does that mean we need boosters? No.”
She added, “and we shouldn’t be giving a valuable resource just because we can,” noting it won’t be possible to stop COVID-19 from coming into the United States unless the virus is stopped around the world.
In his letter, Pfizer CEO Bourla said a decision about boosters should be based on science, not concerns about equitable distribution. The introduction of boosters won’t alter how many doses each country receives, he said.
“No commitments already made by Pfizer to a country will change if boosters are approved,” he said. “We will honor each and every one.”
His letter also noted booster doses were effective against the extremely contagious delta variant, which now accounts for nearly all the COVID-19 infections in the U.S. Studies show adding a third dose – the same vaccine at the same dose of the first two shots – boosts protection against all variants of the virus.
Fauci told the students he’s relieved the original vaccine provides protection against a wide range of variants; otherwise, he said, “you’d be playing whack-a-mole with every new variant.”
A third dose would be as safe as the first two, according toPfizer-BioNTech data, with roughly the same side-effect profile. There is no information on third doses in 16 and 17-year-olds, but the companies think they are similar enough to those over 18 that they should be covered by a booster approval as well.
Only Pfizer-BioNTech booster shots are being considered now because their vaccine is fully licensed by the FDA. Moderna and Johnson & Johnson vaccines are still available only under an emergency use authorization.
Moderna, which Fauci said is likely to receive full approval soon, released its own data Wednesday in support of boosters at six months.
One study, from Kaiser Permanente in Southern California, showed the vaccine prevented 87% of cases of COVID-19 and avoided 96% of hospitalizations. About half the people in the study were exposed to the delta variant.
Another study, which has not yet been peer reviewed, followed people who were in the company’s initial study of vaccine effectiveness, in which half the volunteers received the active vaccine and half a placebo. At the end of the trial they were vaccinated as well, meaning they got their shots months after the first group.
Among the more than 14,000 people in each group, those who received their shots earlier were more likely to catch COVID-19 and to develop severe disease. Three people who received earlier shots were hospitalized and one died, suggesting that protection against severe disease begins to wane over time.
There is no data yet on whether people who received the single-dose J&J vaccine need a second shot.
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