The aim of the COVID-19 vaccine clinical development program is to develop a safe and effective vaccine for the prevention of COVID-19. Ad26.COV2.S, a COVID-19 vaccine based on a human replication-incompetent Ad26 vector, constructed to encode the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) virus spike (S) protein, is being developed. The study will consist of: a screening phase (up to 28 days), study period (60-week), and a long-term follow-up period (1 additional year). The total study duration will be maximum 2 years and 3 months for the participants. Assessments for efficacy (COVID-19 signs and symptoms, etc.), immunogenicity (such as humoral immune responses), and safety (such as adverse events [AEs] monitoring) will be performed throughout the study.
The study will evaluate the efficacy of Ad26.COV2.S in the prevention of molecularly confirmed moderate to severe/critical coronavirus disease-2019 (COVID-19), as compared to placebo, in SARS-CoV-2 seronegative adults in the double-blind phase and to describe COVID-19 outcomes, safety, and immunogenicity in the different study cohorts in open-label phase.