Association between COVID‐19 and consistent mask wearing during contact with others outside the household—A nested case–control analysis, November 2020–October 2021

BACKGROUND: Face masks have been recommended to reduce SARS‐CoV‐2 transmission. However, evidence of the individual benefit of face masks remains limited, including by vaccination status. METHODS: As part of the COVID‐19 Community Research Partnership cohort study, we performed a nested case–control analysis to assess the association between self‐reported consistent mask use during contact with others outside the household and subsequent odds of symptomatic SARS‐CoV‐2 infection (COVID‐19) during November 2020–October 2021. Using conditional logistic regression, we compared 359 case‐participants to 3544 control‐participants who were matched by date, adjusting for enrollment site, age group, sex, race/ethnicity, urban/rural county classification, and healthcare worker occupation. RESULTS: COVID‐19 was associated with not consistently wearing a mask (adjusted odds ratio [aOR] 1.49; 95% confidence interval [CI] [1.14, 1.95]). Compared with persons ≥14 days after mRNA vaccination who also reported always wearing a mask, COVID‐19 was associated with being unvaccinated (aOR 5.94; 95% CI [3.04, 11.62]), not wearing a mask (aOR 1.62; 95% CI [1.07, 2.47]), or both unvaccinated and not wearing a mask (aOR 9.07; 95% CI [4.81, 17.09]). CONCLUSIONS: Our findings indicate that consistent mask wearing can complement vaccination to reduce the risk of COVID‐19.