Table 4.

Main epidemiological indicators of COVID-19 research articles in January 2020

Indicators	Description
Age of patients	• Cases range between 25 and 89 years, with most patients aged between 35 and 55 years and fewer cases among children and infants [14]
	• Median age of patients is 59 years, ranging from 51 to 89 [2]
	• Average age of patients was 55.5 years; age distribution: ≤ 39: 10%; 40–49: 22%, 50–59: 30%; 60–69: 22%, ≥ 70: 15% [19]
	• Cases range from 2 to 72 years [20]
Sex of patients	• More cases were males [20]
	• 59% males [2]
	• 68% males [19]
Age of the deaths	• Median age of death was 75 (with a range between 48 and 89 years) [21]
Exposure history	• Huanan Seafood Market in Wuhan [19, 22]
	• Wuhan residents or people who visited Wuhan [20]
Incubation time	• 4.8 ± 2.6 days (2–11 days) [15]
	• 5.2 days (4.1–7 days) [2]
	• Average of 7 days (2–14 days) [23]
	• Average of 10 days [22]
	• 5–6 days [24]
	• Average of 6.4 days (5.6–7.7 days) [20]
Basic Reproduction (R0)	• 2.6 (uncertainty range: 1.5–3.5) [25]
	• 3.8 (95% CI: 3.6–4.0) [26]
	• 2.2 (1.4–3.8) [27]
	• 4.71 (4.50–4.92) [24]
	• 2.68 (95% CI: 2.47–2.86) [28]
Susceptible populations	• Elderly people [21]
	• People with poor immune function [2]
	• People with chronic co-morbidities [2, 15, 19, 21]
	• People with long-term use of immunosuppressive agents [19]
	• Surgery history before admission [21]
Mortality rate	• 3% (between 29 December 2019 to 23 January, 2020) [15]
	• 2.3% (as of 28 January 2020) [29]
	• 2.8% (as of 25 January, 2020) [21]
	• 2.9% (as of 25 January, 2020) [30]
	• 11% (as of 25 January, 2020) [19]
	• 3.1% (as of 24 January 2020) [31]