Study Design and Participants

• Multicenter, randomized, double-blind, placebo-controlled trial
• Evaluating safety, reactogenicity and immunogenicity of Ad26.COV2.S at intramuscularly at doses 5x10^10 or 1x10^11 vp -Single dose or two-dose schedules 8 weeks apart
• Cohort 1a &1b of adults aged 18-55 and Cohort 3 adults > 65 years old Randomization and Blinding
• Patients randomly assigned to either one dose or two dose schedule with all possible combinations of high dose, low dose and placebo -Sponsor and Statisticians group-unblinded for interim analysis after 29 day visit. Procedures
• S-specific binding bodies were measured by ELISA
• SARS-COV2 neutralizing antibody tigers measured in microneutralization wtVNA
• SARS-COV2 S-specific T cell responses were measured by ICS Statistical Methods