RSV Vaccine Keeps Older People Out of the Hospital

A study published in JAMA earlier this months found the RSV vaccine to be 75% effective in preventing hospitalizations due to RSV-associated illness. Researchers at the Centers for Disease Control and Prevention (CDC) reported findings to support the ongoing risk-benefit analysis of RSV vaccines for older adults.

Prelicensure randomized trials did not assess vaccine efficacy against RSV-associated hospitalization nor did they include immunocompromised patients and underrepresented groups at risk for severe disease, including adults aged 75 years and older. The lack of this specific information served as the impetus for the CDC-guided study.

The case-control analysis study evaluated the effectiveness of the RSV vaccine against RSV-associated hospitalization among adults aged 60 years and older during the first season of RSV. The study group included adults 60 years and older hospitalized with acute respiratory illness from October 2023 to March 2024 and had received virus testing within ten days of illness onset.

The test group consisted of those who had tested positive for RSV only, and the control group included those who had tested negative for RSV, SARS-CoV-2 (the virus that causes COVID-19) and influenza. Vaccination status was retrieved from electronic medical records, immunization registries, and patient self-reporting.

Vaccinated patients were more frequently older, White, immunocompromised, had outpatient visits in the past year and resided in communities with a lower Social Vulnerability Index score compared with unvaccinated patients. ​

Of the 2,978 patients included in the, study, 367 of those hospitalized tested positive for RSV and nearly all of that group — 97.5% — had not been vaccinated. In the control group of the 2,611 of hospitalized patients who tested negatve for RSV, as well as SAR-CoV-2 and influenza, 90.2% had not been vaccinated.

Lead author Diya Surie, M.D., of the Coronavirus and Other Respiratory Viruses Division at CDC and colleagues, used those results to calculated the vaccine's effectiveness at preventing RSV-associated hospitalizations, which came out to be 75% in the 60 and older age group. It was essentially the same (76%) when they narrowed the group to those 75 and older.

The CDC findings support the initial vaccine trials in two critical ways. First, the vaccine protects against RSV-associated hospitalization, estimated to occur annually in 60,000 to 160,000 cases among adults aged 65 years and older in the US. Second, the study shows the vaccine's effectiveness in a population at higher risk of severe RSV disease, including adults aged 75 years and older and individuals with conditions that weaken their immune systems.

Surie and colleagues noted the limitations of the study — it was pubilished as a research letter, not a full-fledged study — such as differences in RSV vaccine uptake and low uptake in the first season, which could affect how widely the findings can be applied and the possibility of remaining uncertainty due to factors that were not measured.

There are three FDA approved RSV vaccines for adults aged 60 years and older are Arexvy, Abrysvo and mRESVIA.