FDA authorizes Pfizer's vaccine booster for seniors, those at high risk for severe Covid-19
The Biden administration’s goal of kicking off its booster shot drive for the entire US population this week is not quite going as planned.
First, Pfizer applied for approval of a supplemental application for the booster shots, but since last Friday’s adcomm reviewing them, the plan has devolved into an EUA, which the FDA issued late Wednesday evening.
The population that is now eligible for the booster, six months after receiving the first pair of Pfizer-BioNTech vaccines, also narrowed from what Pfizer applied for (everyone who’s eligible for the initial Pfizer shots) to just those who are 65 or older, or at high-risk of a Covid infection, including health care workers and others with occupational hazards.
“After considering the totality of the available scientific evidence and the deliberations of our advisory committee of independent, external experts, the FDA amended the EUA for the Pfizer-BioNTech COVID-19 Vaccine to allow for a booster dose in certain populations such as health care workers, teachers and day care staff, grocery workers and those in homeless shelters or prisons, among others,” acting FDA commissioner Janet Woodcock said in a statement.
The agency said it’s relying on an analysis from Pfizer showing that over the last two months, the incidence of Covid-19 was higher among the trial participants who completed their primary vaccine series earlier, compared to participants who completed it later.
“The FDA determined that the rate of breakthrough COVID-19 reported during this time period translates to a modest decrease in the efficacy of the vaccine among those vaccinated earlier,” the agency said.
And for those receiving the boosters due to high risk of severe Covid-19 and institutional or occupational exposure risk, they must be adult, 18 through 64 years of age, which excludes the 12-18 age group for which the vaccine is either authorized or approved.
The EUA follows close debate and disagreement among vaccine experts advising the FDA, and the FDA’s own internal vaccine experts.
The FDA’s adcomm on vaccines roundly rejected the Pfizer/BioNTech booster shots for all individuals older than 16 by a 16-2 vote Friday afternoon. Soon after, however, the agency posed a new question to committee members on limiting booster use to the 65-and-older population and individuals at high risk of disease due to occupational exposure or comorbidities (which is what the agency inevitably went with).
That question, coming roughly 45 minutes after the first, passed through the adcomm with a unanimous 18-0 vote. This vote centered on an EUA — not the sBLA for which Pfizer had applied. While CBER head Peter Marks allowed the additional question and vote, which were not on the agenda, top CBER official Marion Gruber questioned the move. Gruber and her deputy Phil Krause are retiring soon, at least in part due to the administration’s over-stepping its bounds on the booster decision, they wrote in the Lancet last week.
Krause also questioned Pfizer at the adcomm on certain statistical discrepancies that showed its vaccine’s efficacy plummeted to about 60%, whereas his analysis through a different mathematical process using cases per person-years resulted in 93% efficacy. These disparate figures, Krause said, came from the same number of cases in a study by Kaiser Permanente.
The CDC’s ACIP committee will meet Thursday to discuss its recommendation on who specifically should access boosters.