A recent study conducted by researchers led by Diya Surie, MD, from the CDC in Atlanta, revealed promising results regarding the effectiveness of respiratory syncytial virus (RSV) vaccination in adults aged 60 and over. The study, published in JAMA, reported a vaccine effectiveness of 75% against RSV-associated hospitalization in older adults from October 2023 to March 2024. This finding signifies a significant reduction in the risk of hospitalization due to RSV in this age group.
Based on the study’s results, the CDC recommends a single dose of RSV vaccine for all adults aged 75 and older, as well as for individuals aged 60 to 74 years who are at increased risk for severe RSV disease. This recommendation aligns with the high efficacy demonstrated by RSV vaccines in prelicensure randomized trials. However, it is important to note that the trials were not originally designed to assess efficacy against RSV-associated hospitalization, leading to some limitations in the data.
The current study expands upon the prelicensure trial data by providing evidence of vaccine protection against RSV-associated hospitalization. This is particularly significant as an estimated 60,000 to 160,000 cases of RSV-associated hospitalization occur annually among U.S. adults aged 65 years and older. Furthermore, the study demonstrates vaccine protection in a population that more accurately represents those at high risk of severe RSV disease, including individuals aged 75 years and older and those with immunocompromising conditions.
The study included 2,978 adults aged 60 and over, with 367 representing case patients who were hospitalized due to RSV, and the remaining participants acting as controls. The individuals had a median age of 72, a median Charlson Comorbidity Index score of 5, and 24.2% of them were immunocompromised. Participants were hospitalized with acute respiratory illness at various healthcare facilities across 19 states and underwent clinical respiratory virus testing within 10 days of illness onset.
Vaccination Status
RSV vaccination status was determined based on receiving the vaccine 14 days or more before illness onset. Out of the participants, 2.5% of case patients and 9.8% of control patients were vaccinated against RSV. Vaccinated patients were more likely to be older, white, immunocompromised, and have had an outpatient visit in the past year. The median interval between vaccination and illness onset was 84 days.
Despite the promising results, the study acknowledged certain limitations that may impact the generalizability of the findings. Disparities in vaccine uptake and low vaccination rates in the first season of use could influence the outcomes. Additionally, the potential for residual confounding from unmeasured factors may have affected the results.
The study highlights the importance of RSV vaccination in older adults as a means of reducing the risk of severe outcomes such as hospitalization. The findings contribute valuable insights into the effectiveness of RSV vaccines in a high-risk population and provide further support for current vaccination recommendations. Further research and monitoring are essential to continue evaluating the long-term impact of RSV vaccination in older adults.
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