Characteristics of participants
Because of the reopening of China and the lifting of the COVID-19 restrictions on 7 December 2022, the study participants left study sites and our study ended early before our target sample size was met. In total, 1694 participants at 21 construction sites were screened and were confirmed to contact with a SARS-CoV-2 infected individual within 72 h of RT–PCR positive results of an index case. Of which, 60 were ineligible or withdrew early from study before study drug administration, and 1634 were randomized in a ratio of 3:1 to receive SA58 or placebo. After excluding 401 participants not administrated and 11 participants lost to follow-up, 1222 participants entered the full analysis set, with 901 participants in SA58 group and 321 in placebo group (Participant disposition.In the full analysis set, the median age was 46 years (interquartile range, IQR = 35–52 years) in SA58 group and 46 years (IQR = 35–52 years) in placebo group, Baseline characteristics of study participants (full analysis set).Note: IQR: interquartile range.