The Effectiveness of RSV Vaccination in Older Adults

Respiratory syncytial virus (RSV) is a common respiratory virus that can be serious for older adults, leading to hospitalization and even death. A recent study conducted by researchers led by Diya Surie, MD, from the CDC in Atlanta, examined the effectiveness of RSV vaccination in older adults during the first season of use. The results of this test-negative, case-control study are promising, showing a substantial reduction in the risk of hospitalization among older adults who received the RSV vaccine.

The study found that the vaccine was 75% effective against RSV-associated hospitalization in adults aged 60 and over from October 2023 to March 2024. This effectiveness remained consistent even when accounting for potential confounders, with an estimated effectiveness of 79%. The vaccine also showed a similar level of protection across different age groups, with effectiveness rates of 75% for adults aged 60 to 74 years and 76% for those aged 75 and older.

Based on the findings of this study, the CDC recommends a single dose of the RSV vaccine for all adults aged 75 and older, as well as for those aged 60 to 74 years who are at an increased risk for severe RSV disease. This recommendation aligns with previous guidelines established by the agency in 2023, which were based on the high efficacy of the vaccine demonstrated in prelicensure trials.

The study included 2,978 adults aged 60 and over, with 367 representing the case patients and the rest serving as controls. Among the RSV cases, 73% were of the RSV B subtype. The participants had a median age of 72, a median Charlson Comorbidity Index score of 5, and 24.2% of them were immunocompromised. The individuals were hospitalized with acute respiratory illness at various hospitals across 19 states and were tested for RSV, SARS-CoV-2, and influenza.

Although the results of the study are promising, there are some limitations to consider. One key limitation is the disparities in vaccine uptake, as only 2.5% of case patients and 9.8% of control patients were vaccinated. This low uptake in the first season of use may impact the generalizability of the findings. Additionally, the potential for residual confounding from unmeasured factors could also affect the interpretation of the results.

The study provides valuable insights into the effectiveness of RSV vaccination in older adults. The findings highlight the importance of vaccinating older adults against RSV to reduce the risk of hospitalization and severe outcomes associated with the virus. Further research is needed to continue monitoring the long-term effectiveness of the vaccine and to address any potential limitations identified in this study.