Efficacy of RSV vaccine in preventing hospitalization and ER visits in older adults

Respiratory syncytial virus (RSV) infection is a leading cause of severe acute respiratory disease in older adults and adults with underlying comorbidities. It may also result in long-term sequelae and trigger cardiac events. Among US adults aged 65 years or older, approximately 160,000 RSV-related acute respiratory infection hospitalizations and 120,000 emergency room (ER) visits occur annually.Clinical trials have demonstrated high RSV vaccine efficacy against lower respiratory tract disease, but these trials enrolled a smaller proportion of persons aged ≥ 75 years and those with comorbidities compared to general populations in clinical practice settings. Additionally, RSV vaccine efficacy against RSV-related hospitalizations and ER visits has not yet been well described.In a recently published study, U.S. researchers estimated the effectiveness of RSVpreF vaccine (Abrysvo) in older adults. The retrospective case-control study used a test negative design. Cases were adults 60 years of age or older with hospitalizations or ER visits for lower respiratory tract disease in a large US healthcare network in Southern California from November 2023, to April 2024. All cases had respiratory swabs collected and tested for RSV. Two control definitions were prespecified: (1) strict controls included RSV-negative lower respiratory tract disease events that were negative for human metapneumovirus, SARSCoV-2 and influenza, and positive for a nonvaccine preventable cause (primary) and (2) broad controls included all RSV-negative lower respiratory tract disease events (sensitivity analysis). All patients had received RSVpreF vaccine during the first RSV season after the vaccine’s licensure and 21 or more days before the lower respiratory tract disease event. Non-RSVpreF vaccine (e.g., Arexvy) recipients and those who received RSV vaccination less than 21 days before the lower respiratory tract disease event were excluded from analysis. The main outcome was estimated RSVpreF vaccine efficacy against the first episode of RSV-related lower respiratory tract disease hospitalization or ER visit.Results showed the following:A total of 7,047 lower respiratory tract disease-related hospitalizations or ER visits with RSV testing results were included (mean age 76.8 years; 54.2% female; 14.2% immunocompromised; 93.3% with one or more comorbidity).Using strict controls, estimated adjusted vaccine efficacy was 91% (95% CI, 59%–98%).Using broad controls, estimated adjusted vaccine efficacy was 90% (95% CI, 59%–97%).The authors conclude that in this high-risk general population, RSVpreF vaccination conferred protection against RSV-related lower respiratory tract disease in the hospital and ER settings among older US adults; the majority of these adults were ≥ 75 years of age and had comorbidities, and many were immunocompromised. These findings support use of RSVpreF vaccine in older adults.The authors highlight the fact that their results from this general population expand on clinical trial data by documenting vaccine efficacy against more severe outcomes (hospitalization and ER visits) among an older patient population with a higher proportion of high-risk conditions compared with those enrolled in clinical trials. Based on their study results and RSV incidence in older adults, they estimate that for approximately every 250 persons vaccinated, one RSV-related hospitalization or ER visit could be prevented in the first season after RSV vaccination. They emphasize that RSVpreF vaccination of older adults provides an opportunity to reduce severe medically-attended RSV disease burden.ReferenceTartof SY, Aliabadi N, Goodwin G, et al. Estimated vaccine effectiveness for respiratory syncytial virus–related lower respiratory tract disease. JAMA Network Open 2024;7(12):e2450832. (accessed December 17, 2024).

Efficacy of RSV vaccine in preventing hospitalization and ER visits in older adults

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