The efficacy of Ad5-nCoV in preventing virologically confirmed (PCR positive) COVID-19 disease occurring 28 days to 52 weeks after vaccination; regardless of severity;To evaluate the incidence of serious adverse events (SAE) and medically attended adverse events (MAE) within 52 weeks after vaccination in all participants;

The efficacy of Ad5-nCoV in preventing virologically confirmed (PCR positive) COVID-19 disease occurring 28 days to 52 weeks after vaccination; regardless of severity;To evaluate the incidence of serious adverse events (SAE) and medically attended adverse events (MAE) within 52 weeks after vaccination in all participants;