Study highlights importance of RSV vaccination for high-risk populations

Since their introduction last year, researchers have been monitoring the real-world impact of the new respiratory syncytial virus (RSV) vaccines. In a recent commentary in The Lancet, Angela Branche, MD, an infectious diseases researcher at the University of Rochester Medical Center (URMC), details what has been learned during the vaccine's first season.

The evidence is clear; individuals should get vaccinated if they have conditions that place them at risk for severe disease. For older adults and those with chronic conditions, RSV should be considered as serious as the flu, and they should get vaccinated."

Angela Branche, MD, infectious diseases researcher, University of Rochester Medical Center

RSV is a significant cause of severe respiratory illness among older adults, especially those with underlying health conditions. Worldwide, RSV causes millions of infections, hundreds of thousands of hospitalizations, and tens of thousands of deaths annually in adults aged 60 and older. In the US, adults over 65 experience high rates of RSV-related hospital visits, intensive care unit admissions, and deaths. Older people with RSV are at higher risk of severe illness compared to those with influenza or COVID.

Vaccines protect against severe symptoms and keep people out of the hospital

In 2023, the FDA approved three RSV vaccines for older adults. Studies have shown these vaccines to be effective, with the Pfizer, GSK, and Moderna vaccines preventing RSV pneumonia and bronchitis in more than 80 percent of participants.

A recent study published in The Lancet assessed the effectiveness of RSV vaccines using data from a large electronic health record network involving the Centers for Disease Control and Prevention (CDC) and multiple US healthcare systems. The study found that RSV vaccines were 80 percent effective in preventing hospitalization, ICU admission, and death among adults aged 60 and older. Vaccine effectiveness was consistent across age groups, including those 75 and older, and among immunocompromised individuals. The study did not find evidence of waning vaccine protection within the season.

However, the uptake of the RSV vaccine in the 2023-2024 winter season was low. An estimated 24 percent of US adults aged 60 years and older received the vaccine, compared to influenza vaccination rates, which approach 50 percent each year for the same group. "Providers were not sure how to apply the shared clinical decision-making recommendations in the first season, and there remains a general lack of knowledge among the medical community and the public on what constitutes a risk for severe disease and who needs to be protected," said Branche.

Boosting rates and better vaccines

Based on these findings, the US Advisory Committee on Immunization Practices (ACIP), a group of medical and public health experts that advises the CDC, updated guidelines in June 2024 to recommend RSV vaccination for all adults aged 75 and older, those 60 and older in long-term care facilities or with chronic and high-risk health conditions.

"This new data enabled the ACIP to make more definitive recommendations, which will build public confidence in the effectiveness of these vaccines and make implementation a lot easier for providers and pharmacies," said Branche.

New research shows that vaccines that target multiple strains of the RSV virus, called bivalent vaccines, may provide longer protection. URMC infectious disease experts Edward Walsh, MD, and Ann Falsey, MD, helped lead an international study of a bivalent RSV vaccine developed by Pfizer, the results of which were recently detailed in the New England Journal of Medicine. The vaccine effectively prevented severe RSV-related lower respiratory tract illnesses over two RSV seasons, with an overall efficacy of more than 80 percent. The experimental vaccine was particularly effective in individuals aged 60-79.