In the RENOIR trial, an investigational bivalent respiratory syncytial virus (RSV) prefusion F protein–based (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 investigators conclude.
Participants in the phase 3 trial received a single intramuscular dose of RSVpreF vaccine 120 μg (RSV subgroups A and B, 60 μg each) or placebo. The study examined 2 primary endpoints: vaccine efficacy against seasonal RSV-associated lower respiratory tract illness with at least 2 or at least 3 signs or symptoms.
The authors report these results: “At the interim analysis (data-cutoff date, July 14, 2022), 34,284 participants had received RSVpreF vaccine (17,215 participants) or placebo (17,069 participants). 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 of observation) and 33 participants in the placebo group (3.58 cases per 1,000 person-years of observation) (vaccine efficacy, 66.7%; 96.66% confidence interval [CI], 28.8 to 85.8); 2 cases (0.22 cases per 1,000 person-years of observation) and 14 cases (1.52 cases per 1,000 person-years of observation), respectively, occurred with at least three signs or symptoms (vaccine efficacy, 85.7%; 96.66% CI, 32.0 to 98.7). RSV-associated acute respiratory illness occurred in 22 participants in the vaccine group (2.38 cases per 1,000 person-years of observation) and 58 participants in the placebo group (6.30 cases per 1,000 person-years of observation) (vaccine efficacy, 62.1%; 95% CI, 37.1 to 77.9). The incidence of local reactions was higher with vaccine (12%) than with placebo (7%); the incidences of systemic events were similar (27% and 26%, respectively). Similar rates of adverse events through 1 month after injection were reported (vaccine, 9.0%; placebo, 8.5%), with 1.4% and 1.0%, respectively, considered by the investigators to be injection-related. Severe or life-threatening adverse events were reported in 0.5% of vaccine recipients and 0.4% of placebo recipients. Serious adverse events were reported in 2.3% of participants in each group through the data-cutoff date.”
Editorial: “Along with the results of recent trials of other RSV prefusion F vaccines in older adults and of nirsevimab (a monoclonal antibody to the RSV fusion protein) in infants, the results of the RENOIR and MATISSE trials move us closer to prevention of RSV illness in the old and young,” writes an editorialist. “However, critical scientific questions about the RSVpreF vaccine and cross-cutting programmatic questions remain. In older populations, the greatest benefit of RSVpreF vaccine will be prevention of RSV-associated hospitalization and death, but the interim analysis of the RENOIR trial was not powered to address these outcomes. Data regarding protection through a second RSV season and concomitant administration of other vaccines, especially those for influenza and Covid-19, are also needed, as are postmarketing evaluations to assess whether the incidence of serious neurologic outcomes (observed in two recipients of the vaccine) is above the background incidence of these conditions.”