Table 1.

Parameters used in the epidemic models.

Definition	Default value	Range	References
Importing rate for exposed persons	1 every two days only for young population, lasts for 20 days	0-2 cases per day, proportional to the size of population, with larger regions have more imported cases	Arbitrary
Reproduction number, the average number of secondary cases infected by an index case	2.6	1.5–4	[1,20,29,30,32]
Contact rate per capita	10 for young, 7 for old, and 3 for interactions between young and old people	Each with 2–30 contacts range. Senior group living or community gathering is not considered.	[23,33]
Serial interval: duration between infection point (often symptom onset) of index case and the onset of secondary cases infected by him	6 days for young, 4 days for old	3–10 days, average 5 days	[17,19,23,34,35]
Incubation period: duration between exposure and symptom onset	5 days for young, 4 days for old	2–14 days	[36]
Recovery duration	7 days for young and 14 days for old	4–20 days	[45]
Hospitalization rate	5% for young, and 30% for old	5%–50%. average 10% hospitalization among diagnosed, US
Hospital stay	7 days for young, and 21 for old	4–30 days	[13,14,37]
Mortality among hospitalized	5% for young, and 20% for old people	1%–50%	[[13], [14], [15],37,45]