Enhanced safety surveillance of the adjuvanted respiratory syncytial virus vaccine among Italian older adults

An adjuvanted vaccine to prevent lower respiratory tract disease caused by respiratory syncytial virus (RSV) in older adults has recently become available. Post-authorization safety studies (PASSs) conducted under real-world conditions complement data obtained from clinical trials characterized by stringent eligibility criteria. The aim of this PASS study was to evaluate reactogenicity and safety of the novel RSVPreF3 OA, which is currently not included in the Italian immunization schedule. In 2024, adult individuals aged ≥60 years were invited to get vaccinated with a single dose of RSVPreF3 OA. Following vaccination, they were instructed to fill in a diary on the occurrence, grade and duration of local and systemic adverse events (AEs) during the first week post-vaccination. They were also encouraged to notify any other events occurring at any time post-vaccination. The exposure set included 453 adults. Of these, 398 individuals returned valid diaries. At least one solicited AE (generally lasted 1–3 days) was reported by 70.6 % (95 % CI: 65.9–75.0 %) of vaccinees. Injection-site pain was the far most prevalent (60.1 %; 95 % CI: 55.1–64.9 %) solicited AE. Among systemic AEs, malaise/fatigue, headache, arthralgia and myalgia occurred in >10 % of vaccinees, while fever was rare (0.3 %; 95 % CI: 0–1.4 %). Grade 3 severe AEs were registered in 3.5 % (95 % CI: 1.9–5.8 %) of vaccinees. Older age was associated with a lower likelihood of reporting AEs. During a median follow-up of 211 days, no unsolicited serious AEs were registered. This PASS study confirmed an acceptable safety and reactogenicity profiles of RSVPreF3 OA.