Sample size calculations
This study was a secondary data analysis of a cross-sectional study of a subset of Chinese people who turned negative after infection from December 19, 2022 to January 17, 2023. Before the investigation, G*power was used to estimate the minimum sample size, test efficacy (1-β) was set to 0.80, Class I error rate (α) was set to 0.05, and the final sample size was at least 568.