This study was a randomized, double-blinded, placebo-controlled, phase 1 and phase 2 trial conducted in Shangqiu City, China.

• In phase 1 of the trial, healthy individuals who tested negative for antibodies against SARS-CoV-2 were placed into two age categories: one group for 18-59 year olds and another group for 60 years and older. Each individual was then randomly administered a placebo or the vaccine (BBIBP-CorV). The placebo and vaccine were administered through a two dose schedule on days 0 and 28 of the trial in doses of either 2 μg, 4 μg, or 8 μg.
• In phase 2 of the trial, healthy individuals ranging from 18 to 59 years of age were randomly administered either the vaccine or placebo. The placebo and vaccine were administered through a single dose schedule on day 0 with 8 μg or through a two dose schedule on either days 0 and 14, days 0 and 21, or days 0 and 28 in doses of 4 μg.
• The primary outcomes for the trial were tolerability and safety. The secondary outcome was established as immunogenicity against SARS-CoV-2.