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.
Trial registration: ClinicalTrials.gov NCT04342884.
Keywords: COVID-19; SARS-CoV-2; face masks; non-pharmaceutical interventions; vaccination.
© 2023 The Authors. Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.