Self-reported reactogenicity of RSV vaccines among older adults: a post-licensure study within a large integrated healthcare system in Southern California

BACKGROUND: Digital surveys and electronic health records (EHR) can be combined to provide comprehensive assessments of vaccine safety. Limited post-marketing safety data exists for two new RSV vaccines among older adults (Pfizer RSVPreF and GSK RSVPreF3 + ASO1). METHODS: We used digital survey data from adults ≥60 years receiving RSV vaccines through Kaiser Permanente Southern California from November 8, 2023, to February 29, 2024. Enrolled participants received 14-day post-vaccination surveys soliciting local and systemic reactions. Survey results were combined with EHR data. Medical chart reviews were conducted among participants self-reporting receiving medical care for vaccine-related symptoms within 21 days of vaccination. RESULTS: We recruited 14,482 participants aged ≥60 years following RSV vaccination (GSK: 7873 [59%]; Pfizer: 5555 [41%]), including 1054 participants receiving COVID-19 vaccinations on the same day (GSK:618; Pfizer:436). Local and systemic reactions were reported more frequently following GSK vaccinations than Pfizer. The most frequently reported reactions were pain at injection site (56.5% and 14.4%, respectively), fatigue (35.5% and 21.8%), myalgia (26.2% and 13.0%), headache (21.5% and 12.8%) and fever (7.8% and 3.3%). Participants rarely reported seeking medical care (GSK: 158/7873;2.0%; Pfizer: 104/5555;1.9%). Of these, 229 had ≥1 EHR-documented medical encounter 0-21 days post-vaccination, of which 102 (0.8%) were considered possibly related to vaccination (GSK:69; Pfizer:33; RSV + COVID-19:0). Via chart review, the most common diagnoses identified as possibly related to vaccination included respiratory symptoms, such ascough (n = 20 and n = 9, respectively) and congestion (n = 13 and n = 6). No severe events were deemed related to vaccination. Reported reactogenicity symptoms were higher among participants receiving COVID-19 vaccines on the same day compared to participants receiving RSV vaccines alone. CONCLUSION: The most common reactions after RSV vaccines were local pain, fatigue, myalgia, and headache. GSK vaccine recipients containing the AS01E adjuvant reported reactions more frequently than Pfizer vaccine recipients. Consistent with pre-licensure safety data, most symptoms were transient and did not require medical care.