TABLE 5.

Effect of CO on COVID‐19 cases and mortality

Author	Country	Period	Analysis method	Quantified results
Liu et al 2	9 countries	21 Jan to 20 May 2020	Discontinuous linear regression	CO will increase the propagation speed of COVID‐19 infection, which is significant in Korea and China, respectively.
Jiang et al 46	Wuhan in China	25 Jan to 7 Apr 2020	The Pearson's and Poisson's regression models	CO was inversely associated with COVID‐19 deaths.
Wang et al 47	337 prefecture‐level cities in China	NA	Spearman's rank correlation analysis and multiple linear regression	CO was positively correlated with newly confirmed COVID‐19 cases.
Pei et al 48	325 cities in china	Up to 27 May 2020	Geographically weighted regression,	CO had a negative effect on COVID‐19 deaths.
Jiang et al 64	China (Wuhan, Xiaogan, and Huanggang)	25 Jan to 29 Feb 2020	multivariate Poisson's regression	CO was positively correlated with daily incidence in Wuhan (1.932, 95% CI: 1.763‐2.118); but negatively correlated with daily incidence in Xiaogan (0.041, 95%CI: 0.026‐0.066) and Huanggang (0.032, 95%CI: 0.017‐0.063).
Lin et al 78	29 Provinces in China	21 Jan to 3 Apr 2020	Chain‐binomial model, correlation analyses	CO was positively correlated with the basic reproductive ratio of COVID‐19.

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