In a recent publication in the CDC’s Morbidity and Mortality Weekly Report, researchers published the first early real-world clinical safety data for the FDA-approved vaccines. The researchers discovered that the available real-world data are comparable to findings observed in clinical trials, including a very slightly augmented risk of Guillain-Barré syndrome (GBS).

In May 2023, the FDA approved two vaccines for the prevention of RSV lower respiratory tract disease (LTD) in adults aged ≥60 years. Data from clinical trials indicate that GBS was identified as a potential safety concern.

For this study, researchers gathered the first clinical safety data based on real-world data obtained from reports from both V-safe and the Vaccine Adverse Event Reporting System (VAERS). V-safe is a voluntary, active U.S. surveillance system that submits Web surveys to enrolled participants on Days 0 to 7 after vaccination, based on the reported vaccination date. V-safe surveys for adults aged ≥60 years who received an RSV vaccine were available starting October 20, 2023, and daily surveys included questions about local injection-site systemic reactions and other health impacts. Participants reporting medical care for symptoms were also encouraged to submit a VAERS report. VAERS is a voluntary surveillance system that accepts adverse event reports from the public, providers, and manufacturers.

Data reveal that from August 4, 2023, to March 30, 2024, at least 10.6 million U.S. adults aged 60 years and older received a recommended RSV vaccine. From May 3, 2023, to April 14, 2024, the CDC reviewed data reported to V-safe and VAERS after RSV vaccination.

The authors wrote, “Among the 16,220 V-safe participants aged ≥60 years who reported receiving an RSV vaccine and completed one or more daily surveys, 39.0% reported at least one symptom after vaccination; 0.4% of participants reported receiving medical care.”

From May 3, 2023, to April 14, 2024, VAERS received and processed 3,200 reports of adverse events among individuals aged ≥60 years who reported receiving an RSV vaccine. Of the 3,200 VAERS reports, “346 (10.8%) specified a vaccination error (e.g., product administered at an inappropriate site, extra dose administered, or incorrect route of product administration); 64 (2.0%) reports also indicated that an adverse health event had occurred.”

The authors also reported that overall, 2,919 (91.2%) of events reported to the VAERS were classified as nonserious, with commonly reported adverse effects as pain in an extremity (13.2%), headache (12.9%), pain (12.8%), injection-site pain (12.7%), and fatigue (12.2%); however, VAERS recorded 28 reports of GBS that met the established case definition.

The authors wrote, “This review provides early findings from V-safe and VAERS surveillance systems during the first months of RSV vaccine administration among U.S. adults aged ≥60 years. The findings in this report are generally consistent with those from safety data collected in prelicensure clinical trials, including the observance of GBS cases.”

With regard to implications for public health practice, the authors concluded, “On February 29, 2024, ACIP [Advisory Committee on Immunization Practices] announced that based on a thorough review of currently available data, the estimated benefits of RSV vaccination continued to outweigh potential risks. RSV vaccination continues to be recommended for adults aged ≥60 years using shared clinical decision-making. CDC and FDA are conducting active safety evaluations to assess risks for GBS and other adverse events of special interest after RSV vaccination. Results of these studies will help guide future CDC RSV vaccine recommendations.”

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