Efficacy and Safety of Respiratory Syncytial Virus (RSV) Prefusion F Protein Vaccine (RSVPreF3 OA) in Older Adults Over 2 RSV Seasons                                   Clinical Infectious Diseases, ciae010, https://doi.org/10.1093/cid/ciae010

The adjuvanted RSV prefusion F protein–based vaccine (RSVPreF3 OA) was efficacious against RSV-related lower respiratory tract disease (RSV-LRTD) in ≥60-years-olds over 1 RSV season. We evaluated efficacy and safety of 1 RSVPreF3 OA dose and of 2 RSVPreF3 OA doses given 1 year apart against RSV-LRTD over 2 RSV seasons post–dose 1.

Methods: In this phase 3, blinded trial, ≥60-year-olds were randomized (1:1) to receive RSVPreF3 OA or placebo pre–season 1. RSVPreF3 OA recipients were re-randomized (1:1) to receive a second RSVPreF3 OA dose (RSV revaccination group) or placebo (RSV_1dose group) pre–season 2; participants who received placebo pre–season 1 received placebo pre–season 2 (placebo group). Efficacy of both vaccine regimens against RSV-LRTD was evaluated over 2 seasons combined (confirmatory secondary objective, success criterion: lower limits of 2-sided CIs around efficacy estimates >20%).

Results: The efficacy analysis comprised 24 967 participants (RSV_1dose: 6227; RSV revaccination: 6242; placebo: 12 498). Median efficacy follow-up was 17.8 months. Efficacy over 2 seasons of 1 RSVPreF3 OA dose was 67.2% (97.5% CI: 48.2–80.0%) against RSV-LRTD and 78.8% (95% CI: 52.6–92.0%) against severe RSV-LRTD. Efficacy over 2 seasons of a first dose followed by revaccination was 67.1% (97.5% CI: 48.1–80.0%) against RSV-LRTD and 78.8% (95% CI: 52.5–92.0%) against severe RSV-LRTD. Reactogenicity/safety of the revaccination dose were similar to dose 1.

Conclusions: One RSVPreF3 OA dose was efficacious against RSV-LRTD over 2 RSV seasons in ≥60-year-olds. Revaccination 1 year post–dose 1 was well tolerated but did not seem to provide additional efficacy benefit in the overall study population.

Clinical Trials Registration: ClinicalTrials.gov: NCT04886596.

For more information: https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciae010/7585312