Table 2.

Event study regressions of self-reported face mask use, SARS-CoV-2 reproduction numbers, and growth rates of COVID-19 cases on face mask mandates. Percentage point changes are shown for self-reported face mask use and growth rates of COVID-19 cases, and unit changes are shown for SARS-CoV-2 reproduction numbers. Data sources: COVID-19 Trends and Impact Survey, Oxford COVID-19 Government Response Tracker, Our World in Data—COVID-19 data set, and Google COVID-19 Community Mobility Reports.

	Self-reported face mask usea,b (observations=8867)		Reproduction numbera,b (observations=6078)			Case growth ratesa,b (observations=5960)
	Percentage points (SE)	P value	Units (SE)	P value	Percentage points (SE)		P value
ATTc	8.81 (3.08)	.006	−0.31 (0.11)	.008	−0.98 (1.66)		.56
Subgroup mandate	7.33 (4.76)	.13	0.03 (0.09)	.78	1.21 (1.54)		.44
Level-2 mandate	4.49 (4.88)	.36	0.16 (0.11)	.14	1.06 (1.17)		.37
Level-3 mandate	2.43 (4.62)	.60	0.0006 (0.11)	>.99	1.39 (2.13)		.52
School closure	—d	—	−0.02 (0.07)	.74	0.64 (1.01)		.53
Ban on events	—	—	−0.11 (0.05)	.05	0.23 (1.13)		.84
Ban on gatherings	—	—	−0.04 (0.04)	.32	−1.89 (1.27)		.14
Curfew	—	—	0.01 (0.06)	.93	1.49 (1.21)		.22
International travel restrictions	—	—	−0.13 (0.06)	.05	−2.43 (1.17)		.04
Protection of older adults	—	—	0.06 (0.09)	.46	−0.84 (2.89)		.77
Mobility	—	—	0.01 (0)	.10	0.51 (0.14)		<.001
Tests per 100,000 inhabitants	—	—	0 (0)	.07	0 (0)		.02

^aAll models have been estimated with country and time fixed effects.

^bSE (in parentheses) are clustered at the country level.

^cATT: Average Treatment Effect on the Treated. The ATT is obtained by averaging Sun and Abraham [26] interaction-weighted estimates of postmandate period effects.

^dThe model was specified with ATT and subgroup as well as level-2 and level-3 mandate effects, only.