Table 3.

Meta-analysis results of the effect of masks on COVID-19 infection among different subgroups

	Subgroup	Study numbers	OR	95%CI	Heterogeneity
Unadjusted estimates	Overall	6	0.38	0.21-0.69	54.1%
	HCWs	5	0.29	0.18-0.44	11.0%
	Non-HCWs	1	0.72	0.46-1.12	N/A
	China	3	0.21	0.09-0.53	26.1%
	Other countries	3	0.55	0.32-0.95	39.3%
	Mask group*	4	0.44	0.21-0.93	52.0%
	N95 group	2	0.17	0.02-1.69	64.6%
Adjusted estimates	Overall	5	0.19	0.11-0.33	77.6%
	HCWs	4	0.18	0.09-0.34	83.0%
	Non-HCWs	1	0.23	0.09-0.59	N/A
	China	3	0.06	0.02-0.17	81.4%
	Other countries	2	0.3	0.16-0.57	0.0%
	Mask group*	3	0.19	0.09-0.38	0.0%
	N95 group	2	0.2	0.09-0.44	94.3%

HCW, Healthcare workers; Non-HCWs, Nonhealthcare workers; N/A, Not applicable

^⁎Specific type of mask was not reported.