A large-scale study found the respiratory syncytial virus prefusion F vaccine was 91% effective at preventing RSV-related hospitalizations and emergency department visits among adults aged 60 years and older.
The retrospective case-control study, conducted at Kaiser Permanente Southern California from November 2023 to April 2024, analyzed data from 7,047 lower respiratory tract disease (LRTD) encounters. Using strict control definitions, researchers found an adjusted vaccine effectiveness of 91%. A broader analysis showed similar results with 90% effectiveness.
The study population included a higher proportion of individuals at elevated risk for severe RSV disease compared to previous clinical trials. The mean age was 76.8 years, with 57.4% of participants aged 75 or older. Additionally, 93.3% had at least one chronic medical condition, and 14.2% were immunocompromised.
Researchers calculated that vaccinating approximately 250 persons could prevent one RSV-related emergency department visit or hospitalization in the first season after vaccination.
The investigation employed enhanced testing methods by salvaging respiratory specimens collected for standard SARS-CoV-2 and influenza testing. This approach increased the study size and enabled a more robust analysis of emergency department outcomes.
Among the study population, 3.2% had received the respiratory syncytial virus prefusion F (RSVpreF) vaccine, which was lower than national estimates. The researchers noted this may have reflected the vaccine's recent introduction.
The study represented the first major real-world effectiveness analysis of RSVpreF vaccination since its licensure in 2023. The findings were particularly relevant given recent Advisory Committee on Immunization Practices recommendations for RSV vaccination in adults aged 75 and older and those aged 60-74 with increased risk factors for severe disease.
Pfizer funded the study. Kaiser Permanente Southern California led the conduct and data analysis, while both organizations participated in data interpretation.
Potential conflict of interest disclosures can be found in the study.
Reference:
Tartof SY, Aliabadi N, Goodwin G, et al. Estimated vaccine effectiveness for respiratory syncytial virus–related lower respiratory tract disease. JAMA Netw Open. 2024;7(12):e2450832. doi:10.1001/jamanetworkopen.2024.50832
