In June 2023, the Centers for Disease Control and Prevention (CDC) recommended respiratory syncytial virus (RSV) vaccination for adults aged 60 years and older based on high efficacy against RSV lower respiratory tract disease demonstrated in prelicensure randomized trials. Prelicensure trials were not powered to assess efficacy against RSV-associated hospitalization, excluded immunocompromised patients, and underrepresented other groups at increased risk of severe RSV disease, including adults aged 75 years and older. This study by Surie, et al. (2024) evaluated RSV vaccine effectiveness (VE) against RSV-associated hospitalization among adults aged 60 years and older during the first season of use.

Adults aged 60 years and older were eligible for inclusion in this test-negative, case-control analysis if they were hospitalized with acute respiratory illness at 1 of 24 hospitals in 19 U.S. states participating in a surveillance network from Oct. 1, 2023, to March 31, 2024, and had clinical respiratory virus testing within 10 days of illness onset. Nasal swabs were obtained and systematically tested by reverse transcription polymerase chain reaction for RSV, SARS-CoV-2, and influenza viruses. Case patients tested positive for RSV only and control patients tested negative for RSV, SARS-CoV-2, and influenza.

Demographic and clinical data were obtained through patient interview and electronic medical record review. RSV vaccination status was determined from electronic medical records, immunization registries, and self-report and was defined as RSV vaccine receipt 14 days or more before illness onset.

Of 2978 adults aged 60 years and older, 367 (12.3%) were RSV case patients and 2611 (87.7%) were control patients. Median (IQR) age was 72 (66-80) years, median (IQR) Charlson Comorbidity Index score was 5 (4-7), and 720 (24.2%) were immunocompromised (Table). Among 288 RSV case patients with known RSV subtype, 210 (72.9%) were RSV B. A total of 9 of 367 (2.5%) case patients and 256 of 2611 (9.8%) control patients were vaccinated with a median (IQR) interval between vaccination and illness onset of 84 (54-125) days. Compared with unvaccinated patients, vaccinated patients were more frequently older (median age, 75 vs 72 years; P < .001), White (82.6% vs 60.7%; P < .001), immunocompromised (31.7% vs 23.4%; P < .01), had outpatient visits in the past year (95.9% vs 90.1%; P < .01), and resided in communities with a lower Social Vulnerability Index score (median, 0.37 vs 0.58; P < .001). VE against RSV-associated hospitalization was 75% (95% CI, 50%-87%) and did not differ when estimated with inverse probability of vaccination weighting (79% [95% CI, 56%-90%]) or among adults aged 60 to 74 years (75% [95% CI, 31%-91%]) or 75 years and older (76% [95% CI, 40%-91%]).

Reference: Surie D, et al. RSV Vaccine Effectiveness Against Hospitalization Among US Adults 60 Years and Older. JAMA. Published online September 4, 2024. doi:10.1001/jama.2024.15775