Before revision:  The results show that : (1) the lognormal distribution was the most suitable to describe the evolution of epidemic with time . (2) The estimated peak infection time of the reported cases lags behind the peak infection time of the healthcare worker cases, and the estimated infection time interval of the reported cases is smaller than the infection time interval of the healthcare worker cases.
After revision:  The results show that : (1) the lognormal distribution was the most suitable to describe the evolution of epidemic with time ; (2) The estimated peak infection time of the reported cases lags behind the peak infection time of the healthcare worker cases, and the estimated infection time interval of the reported cases is smaller than the infection time interval of the healthcare worker cases.