A large-scale study analyzing data from 14.8 million seniors enrolled in Medicare has found that respiratory syncytial virus (RSV) vaccines are highly effective in preventing RSV-related hospitalizations and deaths in older adults. The vaccines, developed by GlaxoSmithKline and Pfizer, demonstrated an approximate 80% reduction in the risk of these severe outcomes.
Researchers at the U.S. Food and Drug Administration published their findings in the September 18 edition of JAMA Network Open. This study provides robust real-world evidence that complements the results seen in earlier efficacy trials, which had been conducted during periods of lower RSV circulation.
Dr. Edward Walsh, a professor of medicine at the University of Rochester, who was not involved in the new study, described the findings as particularly reassuring due to the vast number of participants. He noted that the real-world effectiveness mirrored the trial results, and both vaccines performed similarly.
Initial concerns that the vaccines might not be as potent in broader populations were addressed by the study. While the analysis initially suggested that recipients were more likely to live in affluent areas and have received other vaccinations like the flu and COVID-19 shots, further analysis confirmed that healthcare access was not the primary driver of the high efficacy. Researchers found that the vaccine's effectiveness remained consistent even after accounting for potential disparities in healthcare access.
Future Vaccine Considerations
One of the ongoing questions in the field is the need for booster shots. Many individuals in the target demographic received their first RSV vaccine in the initial rollout year, leading to lower uptake for a subsequently approved mRNA vaccine from Moderna in 2024. Research is currently underway to determine if subsequent doses are necessary to maintain immunity, and how the body's antibody response changes with re-vaccination.
Unlike annual flu shots, which are recommended due to evolving viral strains, the need and efficacy of repeat RSV vaccinations are still under investigation. Immunologists are exploring ways to induce immunity that could potentially protect against multiple respiratory viruses, moving towards broader-spectrum vaccine options in the future.