Immunogenicity and Safety Following 1 Dose of AS01E-Adjuvanted Respiratory Syncytial Virus Prefusion F Protein Vaccine in Older Adults: A Phase 3 Trial
Tino F. Schwarz, Shinn-Jang Hwang, Pedro Ylisastigui, Chiu-Shong Liu, Kenji Takazawa, Makoto Yono, John Ervin, Charles P. Andrews, Charles Fogarty, Tamara Eckermann, Delphine Collete, Magali de Heusch, Nathalie De Schrevel, Bruno Salaun, Axel Lambert, Céline Maréchal, Aurélie Olivier, Phoebe Nakanwagi, Marc Lievens, Veronica Hulstrøm
Abstract
BACKGROUND: The recently approved AS01E-adjuvanted respiratory syncytial virus (RSV) prefusion F protein-based vaccine (RSVPreF3 OA) demonstrated high efficacy against RSV-related disease in ≥60-year-olds. METHODS: This ongoing phase 3 study in ≥60-year-olds evaluates the immune persistence until three years post-RSVPreF3 OA vaccination. Here, we describe interim results on humoral and cell-mediated immunogenicity, reactogenicity, and safety until one year post-dose 1. RESULTS: In total, 1653 participants were vaccinated. One month post-dose 1, neutralization titers increased 10.5-fold (RSV-A) and 7.8-fold (RSV-B) versus pre-dose 1. Titers then declined to levels 4.4-fold (RSV-A) and 3.5-fold (RSV-B) above pre-dose 1 at month 6, and remained 3.1-fold (RSV-A) and 2.3-fold (RSV-B) above pre-dose 1 levels after one year. RSVPreF3-binding immunoglobulin G levels and CD4+ T-cell frequencies showed similar kinetics. Solicited administration-site and systemic adverse events (mostly mild to moderate and transient) were reported by 62.2% and 49.5% of participants. Serious adverse events were reported by 3.9% of participants within 6 months post-dose 1; one case was considered vaccine-related. CONCLUSIONS: One RSVPreF3 OA dose elicited cell-mediated and RSV-A and RSV-B-specific humoral immune responses that declined over time but remained above pre-dose 1 levels for at least one year. The vaccine was well tolerated with an acceptable safety profile.Clinicaltrials.gov NCT04732871.