Pfizer's Elderly Vaccine Efficacy Drops Slightly After 18 Months, New Clinical Trials Reveal - CDC Advisory Panel Set To Vote Today On Recommended Use Of RSV Shots

Pfizer Inc's PFE vaccine for elderly 60 and above was slightly less effective after 18 months, according to the company's clinical trial results presented on Wednesday.

The Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices (ACIP) will vote today on the recommendation for using new respiratory syncytial virus (RSV) vaccines from GSK Plc GSK and Pfizer.

The data comes from a clinical trial conducted on over 36,000 older adults over two RSV seasons. The latest data is specifically on participants in the Northern Hemisphere at "mid-season two" in the trial, which is around 18 months after vaccination. 

After 18 months, the vaccine demonstrated 78.6% effectiveness in preventing more severe lower respiratory tract illness with three or more symptoms, a slight decline from the 85.7% efficacy observed at one year. 

The vaccine showed about 48.9% effectiveness against the same condition with two or more symptoms after 18 months, indicating a steeper decline than the 66.7% efficacy observed at one year.

GSK plc GSK also released new data from the AReSVi-006 phase 3 trial of a single dose of Arexvy (respiratory syncytial virus vaccine) for older adults, showing that one dose was efficacious against RSV-LRTD and severe LRTD over two full RSV seasons. 

The CDC also provided a cost-effectiveness model for the two shots, showing that GSK's vaccine provided more value—even when priced at $270 per dose compared to $200 for the Pfizer shot.

Price Action: PFE shares are down 0.43% at $39.17 on the last check Wednesday.