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# FDA Hedges Its Position on Covid Vaccine Booster
- URL: https://www.fdaweb.com/fda-hedges-its-position-on-covid-vaccine-booster/
- Published: 2021-09-15T12:00:00.000Z
- Updated: 2026-09-14T17:14:42.000Z
- Author: David McFarland
- Tags: Biologics, #legacy-id-D5150147

In a briefing document prepared for a 9/17 meeting of the FDA Vaccines and Related Biological Products Advisory Committee (VRBPAC) meeting, FDA does not take a position on whether there is a current need for a booster shot of the Pfizer Comirnaty Covid-19 vaccine. “Some observational studies have suggested declining efficacy of Comirnaty over time against symptomatic infection or against the Delta variant,” the [document](https://www.fda.gov/media/152176/download?ref=fdaweb.com) says, “while others have not. However, overall data indicate that currently U.S.-licensed or authorized Covid-19 vaccines still afford protection against severe Covid-19 disease and death in the United States. There are many potentially relevant studies, but FDA has not independently reviewed or verified the underlying data or their conclusions. Some of these studies, including data from the vaccination program in Israel, will be summarized during the 9/21 VRBPAC meeting.”

The agency goes on to say that while observational studies can enable understanding of real-world effectiveness, there are known and unknown biases that can affect their reliability. Due to these biases, it says, some studies may be more reliable than others. “Furthermore,” it continues, “U.S.-based studies of post-authorization effectiveness of BNT162b2 (Comirnaty’s designation during its development) may most accurately represent vaccine effectiveness in the U.S. population,” thus raising questions about the usefulness of Israeli studies supporting booster shots.

FDA says that in support of its application for a booster, Pfizer referenced several observational studies suggesting waning of protection in the setting of the current Delta variant surge among individuals who previously received a two-dose series of primary shots.

The advisory committee is being held, FDA says, “to discuss whether the data Pfizer has submitted are sufficient to support licensure of a booster dose of Comirnaty administered approximately six months after the primary series to individuals 16 years of age and older.”

The advisory committee meeting comes amid concerns being voiced that the Biden administration got ahead of the science in promising booster shots would be available starting this month. Those concerns took on greater [urgency](https://www.fdaweb.com/retiring-vaccine-officials-reluctant-on-boosters/) when two FDA senior vaccine officials decided to retire and wrote a *Lancet* article joining outside researchers in arguing against requiring booster shots until data show a necessary benefit. They also raised the possibility of taking a flu vaccine-type approach to devise a booster vaccine antigen to protect against the variants now circulating. “A similar strategy is used for influenza vaccines, for which each annual vaccine is based on the most current data about circulating strains, increasing the likelihood that the vaccine will remain effective even if there is further strain evolution,” CBER Office of Vaccine Research and Review director **Marion Gruber** and her deputy **Philip Krause** wrote.

Gruber and Krause reportedly had been frustrated by the Centers for Disease Control and its Advisory Committee on Immunization Practices for making decisions on issues that they believe should be reserved for FDA, and by a lack of support from CBER director **Peter Marks**.