RSV vaccine effectiveness in older adults reached high levels against acute respiratory illness in 2023–2024 postlicensure testing.
Study Design and Population
Investigators conducted a retrospective test-negative case-control study among adults aged 60 years and older receiving care in a large integrated health system. The analysis included 8,965 emergency department visits or hospitalizations for acute respiratory illness between 24 November 2023 and 9 April 2024, all with laboratory testing for respiratory pathogens. Case patients were RSV positive. Controls in the primary analysis were negative for RSV, human metapneumovirus, influenza, and SARS-CoV-2 while positive for a non-vaccine-preventable pathogen. Exposure was receipt of the RSVpreF vaccine at least 21 days before the acute respiratory illness diagnosis.
RSV Vaccine Effectiveness Across Subgroups
Among all encounters, 7.8% tested positive for RSV. Vaccination prevalence was 0.3% in cases compared with 3.6% in controls. Adjusted RSV vaccine effectiveness against RSV-related acute respiratory illness leading to emergency department visit or hospitalization was 92% with a 95% confidence interval of 64% to 98%. Effectiveness estimates were similar in patients with risk conditions at 92% with a 95% confidence interval of 65% to 98%, in the oldest subgroup aged 75 years and above at 95% with a 95% confidence interval of 60% to 99%, and in severe clinical presentations.
Clinical Implications for High Risk Older Adults
Protection extended to critical outcomes, including intensive care unit admission, mechanical ventilation, respiratory failure, vasopressor use, or death, with an effectiveness estimate of 90% and a 95% confidence interval of 16% to 99%. Severe disease defined by need for oxygen during an emergency visit or hospitalization showed an effectiveness estimate of 92% with a 95% confidence interval of 35% to 99%. These first-season postlicensure data indicate substantial protection conferred by RSV vaccination in older adults and support vaccination programs focused on high-risk groups who face the greatest burden from RSV-related acute respiratory illness.
Reference: Tartof SY et al. Estimated Vaccine Effectiveness for Respiratory Syncytial Virus-Related Acute Respiratory Illness in Older Adults: Findings From the First Postlicensure Season. Clin Infect Dis. 2025; doi: 10.1093/cid/ciaf496.
