A U.S. Food and Drug Administration (FDA) advisory panel on Friday declined to endorse the Pfizer-BioNTech COVID-19 vaccine booster shot for people ages 16 years and older at least six months following the second dose.
The vote was 2-16.
During the deliberations, panel members suggested older, vulnerable populations may benefit from boosters, but noted insufficient data among younger groups and concerns over potential increased risk for heart inflammation, particularly among males ages 16-17.
The committee was charged with voting whether the safety and effectiveness data from Pfizer’s clinical trial supported approval of the company’s booster dose among people 16 years and older.
The meeting included members of the FDA’s Vaccines and Related Biological Products Advisory Committee, (VRBPAC), as well as officials from the Centers for Disease Control and Prevention (CDC), lsrael’s Health Ministry, vaccine experts and Pfizer representatives.
Dr. William Gruber, senior vice president of vaccine clinical research and development at Pfizer, noted Phase 3 trial data indicating waning protection over time, from 96% vaccine efficacy within two months after the second dose to about 84% by six months and amid the dominant delta variant. While protection dropped against infections, it remained effective in preventing hospitalizations.
Gruber cited evidence suggesting reductions in efficacy owed to waning immunity over time as opposed to the delta variant escaping vaccine protection. Additional data suggested a third Pfizer dose would ramp up protection on par or better than the second dose, however concerns were raised over the potential increased risk of myocarditis. The FDA panel’s review included Pfizer’s trial results with some 300 participants ages 18-55 who received a booster dose about six months after the second dose.
To be clear, the role of the FDA and advisory panel in this case is to determine whether an additional dose can be used, whereas an expert panel advising the CDC (Advisory Committee on Immunization Practices, ACIP), will convene Wednesday to weigh who should receive vaccine and when, following the FDA’s final review. Top health officials last month said this group would likely include health care workers and nursing home residents who were targeted in the earliest phases of the rollout.