Table 1.

The important events related to the outbreak of COVID-19 in Harbin

Date	Event
Mar/19/2020	The American student (H) arrived at Harbin from New York
Mar/27/2020	The dine together including C, G and W (C’s mother) was held
Apr/2/2020	C arrived the second hospital in Harbin and admitted to the hospital
Apr/6/2020	C left the second hospital in Harbin, and arrived at the first
	affiliated hospital of Harbin medical university and admitted to the hospital
Apr/9/2020	One confirmed case and three asymptomatic cases were reported
Apr/10/2020	C was diagnosed with COVID-19
Apr/11/2020	H was diagnosed with COVID-19
Apr/16/2020	Steering group for prevention and control of COVID-19 in Harbin
	was set up by Heilongjiang Provincial Party Committee
Apr/28/2020	H was defined as the infectious source of
	the outbreak of COVID-19 in Harbin
Apr/28/2020	No new infectious case was reported in Harbin