On Nov. 12, 2025, UK researchers reported a test-negative, case-control study across 14 hospitals in England finds that the respiratory syncytial virus (RSV) pre-F (Abrysvo) vaccine helps protect against related hospital admissions in older adults. 

For the study, published in The Lancet Infectious Diseases, the researchers identified 1,006 adults aged 75 to 79 hospitalized with acute respiratory illness (ARI) from October 2024 to March 2025. The participants were predominantly White, with a mean age of 80 years and had a high rate of chronic conditions such as heart and respiratory disease and immunosuppression. 

The researchers noted that while the RSV vaccine has been shown to protect against all-cause RSV-associated hospital admissions, there’s limited data on the vaccine’s effectiveness against different RSV-associated illnesses and complications such as exacerbation of chronic illness.

The researchers found that RSV vaccination was 82.3% effective in protecting against hospital admission for participants with any RSV-associated ARI, 86.7% effective against hospital admissions for those with severe RSV, and 78.8% effective against hospitalization for those with exacerbation of chronic lung disease, heart disease, and/or frailty. 

In patients with lower respiratory tract infections such as pneumonia, vaccine effectiveness (VE) against hospital admissions was 88.6%. For those with exacerbation chronic lung diseases like chronic obstructive pulmonary disease (COPD), VE was 77.4%, and for those with weakened immune systems, VE was 72.8%.

The size of the participant pool didn’t allow for the assessment of VE against more severe outcomes alone, and because the test was conducted as part of routine clinical care, testing procedures at different hospitals may have varied. In addition, residual confounders like the severity of chronic illness may not be accounted for in the data.

The study’s strengths include the test-negative study design, which compares the vaccination status of people who test positive for a disease with those who test negative for it, helping reduce bias from differences in how people seek healthcare for their symptoms.  And rather than use selective testing, which leaves more room for potential bias, the study relied on universal testing of patients with acute respiratory illness.