Before revision:  After estimating the serial interval of COVID-19 from 105  pairs of the virus carrier and the infected, we calculate the daily effective reproductive number, R, for each of all 100 Chinese cities with more than 40 cases.
After revision:  After estimating the serial interval of COVID-19 from 105 hand-collected pairs of the virus carrier and the infected, we calculate the daily effective reproductive number, R, for each of all 100 Chinese cities with more than 40 cases.