Study Reveals Safety and Effectiveness of RSV Vaccine for Older Adults

Respiratory syncytial virus (RSV) poses a significant health risk to older adults and individuals with underlying health conditions. Recent research published by investigators in JAMA assessed the effectiveness of newly available vaccines in these vulnerable populations, conducting a large case-controlled study involving nearly 800,000 individuals tested for RSV. The findings shed light on the protective benefits of vaccination and potential safety considerations, specifically regarding the risk of Guillain-Barré syndrome.¹

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Currently, the CDC recommends a single dose of any of the FDA-approved RSV vaccines—RSVPreF3 (Arexvy; GSK), RSVpreF (Abrysvo; Pfizer), and mRNA-1345 (mRESVIA; Moderna)—for all adults 75 years and older, along with individuals aged 60 to 74 years who are at increased risk of severe illness.² Recently, CDC’s Advisory Committee on Immunization Practices (ACIP) voted to expand its RSV vaccine recommendation to patients aged 50 to 59 years who are at an increased risk for RSV-associated lower respiratory tract disease (LRTD).³

Research published in the Mortality and Morbidity Weekly Report highlighted gaps in the existing data regarding RSV vaccination in older adults, particularly concerning vaccine effectiveness in specific immunocompromised subgroups and a precise understanding of major adverse events like Guillain-Barré syndrome and immune thrombocytopenic purpura. Due to these results, the study authors emphasized the necessity for updated safety analyses from the complete 2023-2024 RSV season to solidify current vaccination recommendations for this age group.¹

Using a data platform containing electronic health records for more than 270 million individuals across the United States, the researchers conducted a test-negative case-control study that was used to evaluate vaccine effectiveness. Additionally, a self-controlled case series of vaccine recipients was included to assess vaccine-associated adverse events.¹

A total of 787,822 patients aged 60 years or older with acute respiratory infection (ARI) were included and were tested for RSV between October 2023 and April 2024 for the vaccine effectiveness portion of the study. Among the total participants, all individuals aged 60 years or older who received an RSV vaccine from July 1, 2023, to June 30, 2024, were included in the safety analysis. The researchers analyzed the data from August 2024 to March 2025.¹

Vaccination status was defined as having received the vaccine at least 2 weeks prior to testing. Vaccine effectiveness against RSV-related ARI, emergency department or urgent care visits, and hospitalizations was calculated using a specific formula. The researchers also determined the increased risks of immune thrombocytopenic purpura and Guillain-Barré syndrome within the 6 weeks following vaccination.¹

The results demonstrated that out of the 787,822 individuals tested for RSV, 53,963 were positive and 733,859 were negative, with 2.4% of cases (positive for RSV) and 9.1% of controls (negative for RSV) being vaccinated. The overall vaccine effectiveness against ARI illness was 75.1%, consistent across age groups and against urgent care visits or hospitalizations. Immunocompromised patients showed a slightly to moderately reduced vaccine effectiveness, with the lowest effectiveness observed in stem cell transplant recipients.¹

Additionally, among over 4.7 million vaccine recipients, no increased risk of immune thrombocytopenic purpura was found. However, there was a small but statistically significant increase in Guillain-Barré syndrome cases connected with the RSVPreF vaccine, but not with the RSVPreF+AS01 vaccine, according to investigators.¹

“By leveraging the power of real-time access to data in clinical practice on a data platform with more than 270 million patient records, this study provides previously unavailable estimates of vaccine effectiveness for patient subgroups and additional safety data concerning rare adverse events,” the study authors concluded in a news release.¹

REFERENCES

1. Effectiveness and Safety of Respiratory Syncytial Virus Vaccine for US Adults Aged 60 Years or Older. JAMA Network Open. News release. May 9, 2025. Accessed May 19, 2025. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2833776?utm_source=For_The_Media&utm_medium=referral&utm_campaign=ftm_links&utm_term=050925

2. Ferruggia K. RSV in Older Adults: Risks, Prevention, and the Pharmacist's Role. Pharmacy Times. February 14, 2025. Accessed May 19, 2025. https://www.pharmacytimes.com/view/rsv-in-older-adults-risks-prevention-and-the-pharmacist-s-role

3. Ferruggia K. ACIP Votes to Expand Lowering RSV Vaccine Recommendation Age to 50 for High-Risk Adults. Pharmacy Times. April 17, 2025. Accessed May 19, 2025. https://www.pharmacytimes.com/view/acip-votes-to-expand-lowering-rsv-vaccine-recommendation-age-to-50-for-high-risk-adults