FDA on Wednesday authorized booster shots of the Pfizer-BioNTech Covid-19 vaccine for adults 65 years and older and those who are at high risk of severe Covid-19, whether because of their health or their job.

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FDA authorizes boosters for certain groups

FDA's authorization allows some individuals who received a Pfizer-BioNTech vaccine to receive a booster shot after at least six months have passed since their second injection.

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The authorization applies to those age 65 and older, as well as to those at high risk of severe Covid-19 because of their health or because of their "frequent institutional or occupational exposure."

According to acting FDA Commissioner Janet Woodcock, the latter group includes "health care workers, teachers and day care staff, grocery workers, and those in homeless shelters or prisons, among others." 

When asked why Woodcock mentioned specific groups who are considered eligible for booster shots, Peter Marks, FDA's top vaccine regulator, said it was important to give examples of groups who are at an increased risk.

"If she hadn't put that there, what would your first question have been?" he said. "Who are you talking about?"

Clay Marsh, the Covid-19 czar for West Virginia, praised the authorization, saying his state's successes in quickly vaccinating older people meant they were due for renewed protection.

Marsh added that hospitals strained by surges in patients couldn't afford to lose staff, and that providing health care workers with booster shots could protect them from mild Covid-19 that would otherwise force them to stay home.

"Anxious would be an understatement," Marsh said of those waiting for booster shots. "We've asked them to be patient with us. We've gotten texts and emails from people saying they're living like hermits again with delta variant, asking when is it going to be safe."

Following FDA's authorization, CDC is expected to issue public health guidance

FDA's authorization paves the way for providers to give booster shots to those who fit the eligibility criteria.

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But although the shots are now authorized, CDC has yet to issue public health guidance on boosters to public health officials and clinicians. That recommendation—which could include greater clarity on who qualifies as an individual at high risk of severe Covid-19—is expected today from the agency's Advisory Committee on Immunization Practices (ACIP).

ACIP is currently in the midst of a two-day meeting regarding booster shots. During Wednesday's meeting, ACIP members noted that, while it's clear a third dose of the Pfizer-BioNTech vaccine increases antibody levels, it's unclear how long that additional protection lasts, whether it increases protection against severe Covid-19, and whether it can decrease transmission of the virus.

"I don't think there's any hope that vaccines such as the ones we have will prevent infection after the first, maybe, couple weeks that you have those extraordinary immediate responses," Sarah Long, a pediatric infectious disease expert at Drexel University College of Medicine, said.

Experts on the committee also noted that limited safety data exists for booster shots, especially in young people—although serious side effects have been exceedingly rare among those who've received Covid-19 vaccines so far.

Some members also expressed concerns about recommending booster shots for only the Pfizer-BioNTech vaccine. Long said there would be a "big public health panic" if those who received vaccines other than the Pfizer-BioNTech shot were unable to get booster shots.

Still, ACIP members emphasized that, with or without an extra booster shot, the currently available Covid-19 vaccines remain extremely effective at preventing serious illness and death.

Matthew Daley, an ACIP member and researcher at Kaiser Permanente Colorado, said, "I want to highlight that in September of 2021 in the United States, deaths from Covid-19 are largely vaccine-preventable with the primary series of any of the three vaccines available." (Axios, 9/22; Weiland/LaFraniere, New York Times, 9/22; Mandavilli, New York Times, 9/23; Branswell, STAT News, 9/22; Gardner, Politico, 9/22; Walker, MedPage Today, 9/22; AP/Modern Healthcare, 9/22)