FRIDAY, Sept. 12, 2025 (HealthDay News) -- The respiratory syncytial virus (RSV) vaccine reduces RSV-associated hospitalization among older adults over two seasons, according to a study published online Sept. 3 in JAMA Network Open.Diya Surie, M.D., from the U.S. Centers for Disease Control and Prevention in Atlanta, and colleagues examined RSV vaccine effectiveness against RSV-associated hospitalization among adults aged 60 years or older during two RSV seasons. The test-negative, case-control study included 6,958 adults aged 60 years or older who were hospitalized with acute respiratory illness at any of 26 hospitals in 20 U.S. states during the 2023 to 2024 and 2024 to 2025 RSV seasons. Case patients tested positive for RSV only and controls tested negative for RSV, severe acute respiratory syndrome coronavirus 2, and influenza.Of the 6,958 adults, 11.8 and 88.2 percent were RSV cases and controls, respectively. The researchers found that 7.7 percent of cases and 15.7 percent of controls were vaccinated. The estimated vaccine effectiveness was 58 percent against RSV-associated hospitalization during two seasons and 69 versus 48 percent for same-season versus prior-season vaccination. During two seasons, estimated vaccine effectiveness was significantly lower among immunocompromised than immunocompetent adults (30 versus 67 percent) and for those with cardiovascular disease versus those without (56 versus 80 percent)."Our data show that the beneficial effects of RSV vaccines appear to wane over time," principal author Welsey H. Self, M.D., M.P.H., from Vanderbilt University Medical Center in Nashville, Tennessee, said in a statement. "Redosing the vaccine at some interval after the initial dose could be a strategy to maintain protection over longer periods of time."Several authors disclosed ties to the pharmaceutical industry.Abstract/Full Text.Sign up for our weekly HealthDay newsletter