A Single RSV Vaccine Dose May Confer Long-Term Protection in Seniors, Study Shows

Going into the seasonal virus time of year, respiratory syncytial virus (RSV) continues to be a concern for seniors. This patient population is a major at-risk group for severe RSV. Prior to this year and the approval of 2 vaccines, seniors were without any therapeutic protection. As such, one area of interest has been continuing studies examining the efficacy of these RSV vaccines.

Investigators presented data as a late-breaking abstract at IDWeek 2023 with results around RSV vaccination with the RSV Prefusion F Protein vaccine (RSVPreF3 +AS01E). Specifically, they examined the efficacy of 1 dose of the RSV Prefusion F Protein vaccine in adults 60 years of age or older over the course of 2 RSV seasons.

The phase 3, placebo-controlled, multi-country study randomly assigned participants 1:1 to receive the vaccine or placebo before RSV season 1. Vaccine recipients were then re-randomized 1:1 before RSV season 2 to receive a second vaccine dose (RSV_annual group) or placebo (RSV_1 dose group); participants who received placebo pre-season 1 received an additional placebo dose. Vaccine efficacy against first occurrence of RSV-related lower respiratory tract disease (RSV-LRTD), severe RSV-LRTD, RSV-LRTD by age, baseline comorbidity and frailty status, and RSV-related acute respiratory illness (ARI) was assessed over 2 seasons.

“Of 24,973 participants vaccinated before season 1, 24,967 were included in the current VE analyses (RSV_annual: 6,242; RSV_1dose: 6,227; placebo: 12,498). The median follow-up over 2 seasons was 17.8 months,” the investigators wrote. “VE of a single dose of [the vaccine] against RSV-related lower respiratory tract disease (RSV-LRTD) over 2 seasons was 67.2% (97.5% confidence interval [CI]: 48.2–80.0); VE of annual revaccination over 2 seasons was 67.1% (97.5% CI: 48.1–80.0). Sustained VE was observed over 2 seasons against severe RSV-LRTD, against RSV-LRTD among participants 60–69 years of age (YOA), 70–79 YOA, those with ≥ 1 baseline comorbidity of interest, pre-frail participants and against RSV-ARI. The reactogenicity and safety profile of the second RSVPreF3 OA dose was in line with the first dose.”

This RSV vaccine was FDA approved earlier this year for the prevention of RSV-LRTD in adults ≥ 60 years of age.

In conclusion, the investigators reported a couple of takeaways.

“One dose of [the vaccine] is efficacious against RSV-LRTD in adults ≥ 60 YOA over 2 full RSV seasons, as well as against severe RSV-LRTD, and in adults with advanced ages and underlying comorbidities. Revaccination after 1 year does not appear to confer additional efficacy benefit for the overall population.”

Click here for more coverage of IDWeek 2023.

REFERENCE

Ison M, Papi a, et al. Efficacy of One Dose of the Respiratory Syncytial Virus (RSV) Prefusion F Protein Vaccine (RSVPreF3 OA) in Adults ≥ 60 Years of Age Persists for 2 RSV Seasons. Presented at: IDWeek 2023. October 11-14, 2023; Boston, MA. Abstract 1936.