By Julie Steenhuysen
(Reuters) -A U.S. Centers for Disease Control and Prevention advisory panel could vote on the use of a third shot of Pfizer Inc (NYSE:PFE) and partner BioNTech SE (NASDAQ:BNTX)'s COVID-19 vaccine on Thursday, an agency official said at a public meeting of the panel on Wednesday.
The CDC's Advisory Committee on Immunization Practices (ACIP) is meeting on Sept 22-23 to weigh which populations would most benefit from a third shot as it awaits a decision on authorization by the U.S. Food and Drug Administration.
Pfizer has asked the FDA to approve the third shot for all people aged 16 and over, but a panel of outside advisors to the FDA last Friday said there was only evidence for a shot being needed by people aged 65 and older. The FDA has not yet said how it plans to proceed.
The CDC panel considered presentations from staff showing how the vaccine worked in different age groups and populations, including older adults, those whose jobs put them at increased risk for exposure such as healthcare workers, and adults with underlying medical conditions.
Several of the presentations showed vaccine efficacy in older adults against hospitalization was falling, impacted both by the Delta variant and possible waning of vaccine efficacy over time.
Pfizer officials reviewed the case it presented last week to the FDA advisory panel arguing that a booster is needed for all populations.
CDC staff also reviewed U.S. studies on vaccine effectiveness across U.S. populations and found significant declines in effectiveness against infection for vaccines based on messenger RNA technology during the period when the Delta variant was predominant.
The studies also showed protection from hospitalization declined more in those vaccinated with the Pfizer vaccine than the one made by Moderna (NASDAQ:MRNA) Inc. during the time when the Delta variant was predominant.
Similar patterns of reduced vaccine effectiveness were seen in the general adult population.