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Tracing and isolation of close contacts is used to control outbreaks of coronavirus disease 2019 (COVID‐19) in China. However, risk factors associated with the occurrence of COVID‐19 among close contacts have not been well described. A total of 106 household contacts were included in this study, of whom 19 developed into COVID‐19 cases, and the secondary attack rate was 17.9%. Multivariable analysis showed that increasing risk of occurrence of COVID‐19 among household contacts was associated with female index patients (adjusted hazard ratio [aHR] = 3.84, 95% CI = 1.07–13.78), critical disease index patients (aHR = 7.58, 95% CI = 1.66–34.66), effective contact duration with index patients > 2 days (aHR = 4.21, 95% CI = 1.29–13.73), and effective contact duration > 11 days (aHR = 17.88, 95% CI = 3.26–98.01). The sex and disease severity of index patients with COVID‐19 and longer effective contact duration with patients with confirmed COVID‐19 could help epidemiologists to identify potential COVID‐19 cases among household contacts at an early stage. [ABSTRACT FROM AUTHOR]