1936. 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

Abstract Background RSVPreF3 OA was recently approved by the United States FDA for the prevention of RSV-related lower respiratory tract disease (RSV-LRTD) in adults ≥ 60 years of age (YOA). We present persistence of vaccine efficacy (VE) of a single RSVPreF3 OA dose, along with VE and safety of annual revaccination dose, over 2 RSV seasons. Methods In this phase 3, placebo-controlled, multi-country study (NCT04886596), adults ≥ 60 YOA were randomized 1:1 to receive RSVPreF3 OA or placebo before RSV season 1. RSVPreF3 OA recipients were then re-randomized 1:1 before RSV season 2 to receive a second RSVPreF3 OA dose (RSV_annual group) or placebo (RSV_1dose group); participants who received placebo pre-season 1 received an additional placebo dose (placebo group). VE against first occurrence of RSV-LRTD (confirmatory secondary objectives), severe RSV-LRTD, RSV-LRTD by age, baseline comorbidity and frailty status, and RSV-related acute respiratory illness (ARI) was assessed over 2 seasons. Reactogenicity and safety were also evaluated. Results 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. VE of a single dose of RSVPreF3 OA against 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 YOA, 70–79 YOA, those with ≥ 1 baseline comorbidity of interest, pre-frail participants and against RSV-ARI (Figure 1). The reactogenicity (Figure 2) and safety profile of the second RSVPreF3 OA dose was in line with the first dose. Conclusion One dose of RSVPreF3 OA 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. The second RSVPreF3 OA dose had a clinically acceptable safety profile. The clinical development program will further evaluate persistence and the best timing for revaccination. Funding: GlaxoSmithKline Biologicals SA Disclosures Michael G. Ison, MD MS, Adagio: Advisor/Consultant|Adamis: Advisor/Consultant|Adamis: Board Member|ADMA Biologics: Advisor/Consultant|AlloVir: Advisor/Consultant|AlloVir: Board Member|Atea: Advisor/Consultant|Cidara: Advisor/Consultant|CSL Behring: Board Member|Genentech/Roche: Advisor/Consultant|GSK: Grant/Research Support|Janssen: Advisor/Consultant|Janssen: Board Member|Merck: Board Member|NIH: Board Member|Romark: Advisor/Consultant|Seqiris: Board Member|Shionogi: Advisor/Consultant|Takeda: Advisor/Consultant|Takeda: Board Member|Talaris: Advisor/Consultant|Talaris: Board Member|UpToDate: Stocks/Bonds|Viracor Eurofins: Advisor/Consultant Alberto Papi, MD, Agenzia Italiana del farmaco (AIFA): Grant/Research Support|AstraZeneca: Advisor/Consultant|AstraZeneca: Board Member|AstraZeneca: Grant/Research Support|AstraZeneca: Honoraria|Avillon: Advisor/Consultant|Avillon: Honoraria|Chiesi Farmaceutici: Advisor/Consultant|Chiesi Farmaceutici: Board Member|Chiesi Farmaceutici: Grant/Research Support|Chiesi Farmaceutici: Honoraria|EdmondPharma: Honoraria|Elpen Pharmaceuticals: Advisor/Consultant|Elpen Pharmaceuticals: Honoraria|GSK: Advisor/Consultant|GSK: Board Member|GSK: Grant/Research Support|MENARINI: Honoraria|Mundipharma: Honoraria|Novartis: Advisor/Consultant|Novartis: Honoraria|Qivia: Honoraria|Sanofi: Advisor/Consultant|Sanofi: Board Member|Sanofi: Grant/Research Support|Sanofi: Honoraria|Zambon: Honoraria Joanne M. Langley, MD, GSK: Grant/Research Support|Inventprise: Grant/Research Support|Merck: Grant/Research Support|Moderna: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi: Grant/Research Support|Seqirus: Board Member|Vaxcyte: Data Safety review board|VBI: Grant/Research Support Isabel Leroux-Roels, PhD MD, Curevac: Grant/Research Support|GSK: Board Member|GSK: Grant/Research Support|ICON Genetics: Grant/Research Support|ICON Genetics: Yes|Icosavax: Grant/Research Support|Janssen Vaccines: Advisor/Consultant|Janssen Vaccines: Board Member|Janssen Vaccines: Grant/Research Support|Moderna: Grant/Research Support|MSD: Advisor/Consultant|MSD: Grant/Research Support|OSE Immunotherapeutics: Grant/Research Support|Osivax: Grant/Research Support|Virometrix: Grant/Research Support Federico Martinon-Torres, MD, PhD, Assoc. Prof, Abbot: Principal Investigator in randomized controlled trials|Ablynx: Principal Investigator in randomized controlled trials|AstraZeneca: Advisor/Consultant|AstraZeneca: Grant/Research Support|AstraZeneca: Honoraria|Biofabri: Advisor/Consultant|Biofabri: Board Member|Biofabri: Grant/Research Support|Biofabri: Honoraria|GSK: Advisor/Consultant|GSK: Grant/Research Support|GSK: Honoraria|GSK: Clínical trials fees paid to my institution|Janssen: Advisor/Consultant|Janssen: Grant/Research Support|Janssen: Honoraria|Janssen: Clínical trials fees paid to my institution|Medimmune: Principal Investigator in randomized controlled trials|Merck: Grant/Research Support|Moderna: Advisor/Consultant|Moderna: Grant/Research Support|Moderna: Honoraria|MSD: Advisor/Consultant|MSD: attending meetings and/or travel, Principal Investigator in randomized controlled trials|Novartis: Principal Investigator in randomized controlled trials|Novavax: Honoraria|Pfizer: Advisor/Consultant|Pfizer: Board Member|Pfizer: Grant/Research Support|Pfizer: Honoraria|Pfizer: Clínical trials fees paid to my institution|Regeneron: Principal Investigator in randomized controlled trials|Roche: Principal Investigator in randomized controlled trials|Sanofi: Advisor/Consultant|Sanofi: Grant/Research Support|Sanofi: Honoraria|Sanofi: Clínical trials fees paid to my institution|Seqirus: Principal Investigator in randomized controlled trials Tino F. Schwarz, Prof. Dr. MD, Alexion: Honoraria|AstraZeneca: Honoraria|Bavarian Nordic: Advisor/Consultant|Bavarian Nordic: Honoraria|Biogen: Honoraria|BioNTech: Board Member|BioNTech: Honoraria|GSK: Advisor/Consultant|GSK: Honoraria|Janssen-Cilag: Advisor/Consultant|Janssen-Cilag: Honoraria|Merck-Serono: Advisor/Consultant|Merck-Serono: Honoraria|Moderna: Advisor/Consultant|Moderna: Honoraria|MSD: Honoraria|Novavax: Advisor/Consultant|Novavax: Honoraria|Pfizer: Honoraria|Roche: Honoraria|Sanofi-Aventis: Honoraria|Seqirus: Advisor/Consultant|Seqirus: Honoraria|Synlab: Honoraria|Takeda: Advisor/Consultant|Takeda: Honoraria|va-Q-tec: Honoraria Richard N. Van Zyl-Smit, PhD MD, Boehringer Ingelheim: Grant/Research Support|Boehringer Ingelheim: Honoraria|CIPLA: Honoraria|Glenmark: Honoraria|GSK: Advisor/Consultant|Novartis: Honoraria|OnQsa: Advisor/Consultant Susanna Cuadripani, MD, GSK: GSK Employee Nancy Dezutter, PhD, PharmD, GSK: Patents still under assessment|GSK: GSK Employee|GSK: Stocks/Bonds|Haleon: Stocks/Bonds Olivier Gruselle, MS, GSK: GSK Employee|GSK: Stocks/Bonds Laurence Fissette, Master in Statistics, GSK: RSV vaccine patent|GSK: GSK Employee|GSK: Stocks/Bonds Marie-Pierre David, Master in Statistics, GSK: GSK Employee|GSK: Stocks/Bonds Aurélie Olivier, PhD, GSK: Yes|GSK: GSK Employee|GSK: Stocks/Bonds Marie Van Der Wielen, MD, GSK: GSK Employee|GSK: Stocks/Bonds Dominique Descamps, MD, GSK: GSK Employee|GSK: Stocks/Bonds

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