Respiratory syncytial virus prefusion F (RSVpreF) vaccine significantly reduced severe RSV-related lower respiratory tract disease (LRTD) requiring hospitalization or emergency department (ED) visits in an older adult population, including substantial representation from the oldest age groups.

"Based on our study results and RSV incidence in older adults, for approximately every 250 persons vaccinated, one RSV-related ED or hospitalization encounter could be prevented in the first season after vaccination," the authors wrote.

The study was led by Sara Y. Tartof, PhD, MPH, Department of Research and Evaluation, Kaiser Permanente Southern California, in Pasadena, California. It was published online on December 13, 2024, in JAMA Network Open.

Less than 5% of those with LRTD events were vaccinated in the first season, which may have affected the generalizability of estimates and hindered the stability of vaccine effectiveness estimates for some subgroups. This vaccination rate was lower than that reported in national estimates. The early first season estimates missed the first part of RSV season, restricting follow-up times to 61 and 58 days for the strict and broad control group analyses, respectively.

This study was funded by Pfizer. Several authors declared receiving grants and personal fees from Pfizer paid to the institution outside the current and submitted work. Some authors declared being stockholders of Pfizer.