RSV Vaccine Effectiveness Declines After One Year, Signaling Need for Booster Strategy

Nearly 60% of adults aged 60 and older who received the new RSV vaccine experienced protection against hospitalization during two full respiratory virus seasons, but that protection dipped to under 50% in the second year, according to a new study published in JAMA. This finding isn’t a cause for alarm, but a critical signal that a one-and-done approach to RSV vaccination may not be sufficient for sustained immunity – and could reshape public health recommendations in the years to come.

The Promise of RSV Vaccination for Seniors

Respiratory Syncytial Virus (RSV) is often dismissed as a childhood illness, but it poses a significant threat to older adults. Each year, RSV leads to an estimated 100,000-150,000 hospitalizations and 4,000-8,000 deaths among those 60 and older in the U.S. The recent approval of RSV vaccines marked a major public health victory, offering a new layer of defense against this potentially deadly virus. The study, conducted by the IVY Network – a collaboration of 26 hospitals across 20 states – provides crucial real-world data on the vaccine’s performance.

How the Study Was Conducted

Researchers analyzed data from nearly 7,000 individuals hospitalized with acute respiratory illness between October 2023 and April 2025. Using a “test-negative” study design, they compared vaccination rates among those who tested positive for RSV with those who tested negative for the virus. This allowed them to accurately assess the vaccine’s effectiveness in preventing severe RSV outcomes. The results showed a 69% reduction in RSV-related hospitalizations in the first year post-vaccination, a substantial benefit.

The Waning Effect: Why Boosters May Be Necessary

While the initial protection was impressive, the study revealed a concerning trend: vaccine effectiveness decreased to 48% in the second year. “Our data show that the beneficial effects of RSV vaccines appear to wane over time,” explained Dr. Wesley Self, principal investigator for the IVY Network. This decline isn’t unexpected; immunity from many vaccines diminishes over time, necessitating booster doses. The question now is when and how often should older adults receive RSV boosters?

This waning immunity highlights the complex nature of RSV and the human immune system. Factors like age-related immune decline (immunosenescence) and the evolving nature of the virus itself likely contribute to the reduced effectiveness. Further research is needed to understand these dynamics and optimize vaccination strategies.

Implications for Public Health and Future Research

The findings reinforce current recommendations from the CDC, which advise RSV vaccination for adults 75 and older, and those aged 60-74 with increased risk factors. However, the study’s data on waning immunity will likely fuel discussions about expanding booster recommendations.

Several key areas require further investigation:

• Optimal Booster Timing: Determining the ideal interval between the initial dose and a booster shot is crucial.
• Variant Monitoring: RSV, like other respiratory viruses, can mutate. Ongoing surveillance is needed to ensure the vaccine remains effective against circulating strains.
• Impact of Boosters on Immunocompromised Individuals: Individuals with weakened immune systems may require different vaccination schedules or alternative strategies.

The IVY Network’s research underscores the importance of continuous monitoring of vaccine effectiveness. This data-driven approach will be essential for adapting vaccination strategies and maximizing protection against RSV.

Staying Protected: What You Can Do Now

The emergence of effective RSV vaccines represents a significant step forward in protecting vulnerable populations. While the long-term implications of waning immunity are still being investigated, the current data strongly support vaccination for those eligible. Talk to your healthcare provider about whether the RSV vaccine is right for you, and stay informed about evolving recommendations. The CDC’s website provides the latest information on RSV prevention and vaccination.

What are your thoughts on the potential need for annual RSV boosters? Share your perspective in the comments below!