Mask Wearing and Control of SARS-CoV-2 Transmission in the United States

Abstract

Introduction: Cloth face coverings and surgical masks have become commonplace across the United States in response to the SARS-CoV-2 epidemic. While evidence suggests masks help curb the spread of respiratory pathogens, research is limited. Face masks have quickly become a topic of public debate as government mandates have started requiring their use. Here we investigate the association between self-reported mask wearing, social distancing and community SARS-CoV-2 transmission in the United States, as well as the effect of statewide mandates on mask uptake. Methods: Serial cross-sectional surveys were administered June 3 through July 31, 2020 via web platform. Surveys queried individuals' likelihood to wear a face mask to the grocery store or with family and friends. Responses (N=378,207) were aggregated by week and state and combined with measures of the instantaneous reproductive number (Rt), social distancing proxies, respondent demographics and other potential sources of confounding. We fit multivariate logistic regression models to estimate the association between mask wearing and community transmission control (Rt <1) for each state and week. Multiple sensitivity analyses were considered to corroborate findings across mask wearing definitions, Rt estimators and data sources. Additionally, mask wearing in 12 states was evaluated two weeks before and after statewide mandates. Results: We find an upward trend in mask usage across the U.S., although uptake varies by geography and demographic groups. A multivariate logistic model controlling for social distancing and other variables found a 10% increase in mask wearing was associated with a 3.53 (95% CI: 2.03, 6.43) odds of transmission control (Rt <1). We also find that communities with high mask wearing and social distancing have the highest predicted probability of a controlled epidemic. These positive associations were maintained across sensitivity analyses. Segmented regression analysis of mask wearing found no statistical change following mandates, however the positive trend of increased mask wearing over time was preserved. Conclusion: Widespread utilization of face masks combined with social distancing increases the odds of SARS-CoV-2 transmission control. Mask wearing rose separately from government mask mandates, suggesting supplemental public health interventions are needed to maximize mask adoption and disrupt the spread of SARS-CoV-2, especially as social distancing measures are relaxed.

Face masks help control transmission of COVID-19

“…In their paper on self-reported face mask wearing and control of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission in the US, Rader and colleagues 1 showed an elegant ecological analysis of data from across the US, estimating the effect of face mask use on the transmission of COVID-19 infection. The authors made use of online survey responses of mask usage from thousands of individuals across the country over time to measure the relationship between mask wearing and community transmission control, as characterised by the instantaneous reproductive number.…”

“…The study of Rader and colleagues suggests that, in the US, risk-compensation does not cancel out the positive effect of face masks, but whether the US is representative of other countries is arguable. 1 On a policy level, the possibility of risk compensation, uncertainty about the magnitude of the reduction in transmission due to masks, and the result that the effect of face masks can be even greater when combined with other control measures, means maintaining other measures, such as physical distancing, contact tracing, testing, isolation, and quarantine, is still necessary.…”

Imprecise assessment of mask use may obscure associations with SARS-CoV-2 positivity

“…Mask wearing has been shown to be effective at preventing the transmission of SARS-CoV-2 and remains a key public health intervention for mitigating the COVID-19 pandemic (1,2). Mask wearing requires high population-level compliance (4) and is most effective at preventing onward transmission if both infected and susceptible individuals are wearing a mask at the time of contact (3). Inconsistent mask wearing policies and limited enforcement mechanisms have resulted in differential rates of mask uptake across the United States (2)(3)(4).…”

“…Mask wearing requires high population-level compliance (4) and is most effective at preventing onward transmission if both infected and susceptible individuals are wearing a mask at the time of contact (3). Inconsistent mask wearing policies and limited enforcement mechanisms have resulted in differential rates of mask uptake across the United States (2)(3)(4). Some ecological and individual studies have found associations with reported mask wearing and changes in the SARS-CoV-2 transmission rate or self-reported positivity (1,4,5).…”

“…Inconsistent mask wearing policies and limited enforcement mechanisms have resulted in differential rates of mask uptake across the United States (2)(3)(4). Some ecological and individual studies have found associations with reported mask wearing and changes in the SARS-CoV-2 transmission rate or self-reported positivity (1,4,5). To date, the majority of these studies have only asked, general questions about whether or not a person wears a mask when outside the home with options capturing varying degrees of adherence (e.g., always, sometimes, occasionally, and never) (5).…”