A Trial Investigating the Safety and Effects of One BNT162 Vaccine Against COVID-19 in Healthy Adults

This study was a multi-site, Phase I/II, open-label, dose-escalation study. The study included the first in human dose and dose ranging groups in healthy younger participants (aged 18 to 55 years \[yrs\]) and older participants (aged 56 to 85 yrs). The conducted Part A followed a dose escalation design. Discretionary dose de-escalation and refinement was also planned. Study participants with the first-in-human \[FIH\] immunization and any subsequent dose escalation cohorts were immunized using a sentinel dosing/subject staggering. For any dose de-escalation or dose-refinement cohorts in younger adults, i.e., cohorts with doses lower than previously tested, participants were dosed using a subject staggering process. Cohorts in older participants were optional and dependent on acceptability of dosing in younger participants. Part A consisted of a treatment phase (screening to Visit 7) and a follow-up phase (Visits 8 to 10).