MONDAY, April 10, 2023 (HealthDay News) — The respiratory syncytial virus prefusion F protein-based (RSVpreF) vaccine appears to be safe and effective for preventing RSV-associated lower respiratory tract illness in older adults, according to a study published online April 5 in the New England Journal of Medicine.

Edward E. Walsh, M.D., from the University of Rochester in New York, and colleagues conducted a phase 3 trial in which older adults (60 years and older) were randomly assigned to receive a single intramuscular injection of RSVpreF vaccine (17,215 participants) at a dose of 120 μg (60 μg each of RSV A and RSV B antigens) or placebo (17,069 participants).

The researchers found that RSV-associated lower respiratory tract illness with at least two signs or symptoms occurred in 11 participants in the vaccine group (1.19 cases per 1,000 person-years) and 33 participants in the placebo group (3.58 cases per 1,000 person-years), resulting in a vaccine efficacy of 66.7 percent. Cases with at least three signs of symptoms occurred in two participants receiving the vaccine and 14 receiving placebo (0.22 versus 1.52 cases per 1,000 person-years; vaccine efficacy, 85.7 percent). Twenty-two participants in the vaccine group (2.38 cases per 1, 000 person-years) and 58 participants in the placebo group (6.30 cases per 1,000 person-years) had RSV-associated acute respiratory illness (vaccine efficacy, 62.1 percent). The incidence of local reactions was higher with vaccine than with placebo (12 versus 7 percent), while the incidences of systemic events were similar (27 and 26 percent, respectively). Similar rates of injection-related adverse events through one month were reported (1.4 and 1.0 percent, respectively).

“RSVpreF vaccine prevented RSV-associated lower respiratory tract illness and RSV-associated acute respiratory illness in adults (≥60 years of age), without evident safety concerns,” the authors write.

Several authors disclosed financial ties to Pfizer, which developed the RSVpreF vaccine and funded the study.

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