The effect of face mask mandates during the COVID-19 pandemic on the rate of mask use in the United States

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Abstract

As COVID-19 continues to spread throughout the United States, there has been a search for policies to prevent individual infections, to slow the spread of the virus in general, and to mitigate the economic impact of the pandemic. Masks have proven to be a cost-effective measure in all regards, and as such some state governments have begun to mandate their use. However, while the efficacy of masks has been demonstrated, the efficacy of public policies which mandate the use of masks has not been demonstrated. This paper compares the rates of mask use in counties as defined by state policy. It finds that state mandates are strongly correlated with higher rates of mask use, and that mandating use by all individuals in public spaces is more effective than a less comprehensive mandate for mask use by all public facing employees.

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  1. SciScore for 10.1101/2020.10.03.20206326: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    No key resources detected.


    Results from OddPub: Thank you for sharing your code and data.


    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.


    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.


    Results from JetFighter: We did not find any issues relating to colormaps.


    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  2. Our take

    An individually randomized trial, available as a preprint and thus not yet peer reviewed, in Denmark found no significant differences in COVID-19 infections between adults who received recommendations to wear face masks (1.8%) in congregate settings with limited mask use and those who did not (2.1%). Low self-reported adherence to face mask recommendations suggests these observed associations are attributed more to low intervention compliance and as well as poor study power, and less to suboptimal effectiveness of masks in preventing COVID-19 infection.

    Study design

    Study population and setting

    In April 2020, 6,024 Danish adults with no history of COVID-19 infection who reported spending on average 3 hours every day outside their households were randomized to one of two study arms. The intervention group received a supply of fifty surgical masks (including instructions for proper use) and were recommended to wear these masks in congregate settings outside their homes, while the control group received guidance to follow standard public health recommendations for preventing COVID-19 transmission (e.g. physical distancing, frequent handwashing, avoiding crowded public settings). At the time of study, mask use in community settings was low. All participants received materials and instructions for SARS-CoV-2 point-of-care antibody (IgM and IgG) testing in their homes at baseline and after 1-month follow-up as well as RT-PCR oropharyngeal testing at 1-month follow-up (or following COVID-19 symptom onset during the study period). Participants responded to weekly follow-up emails to report antibody test results, COVID-19 symptoms, and compliance with face mask recommendations (intervention group only), measured by self-reported “complete” adherence, “predominant” adherence, or non-adherence in the past week.

    Summary of main findings

    Fewer than half (46%) of participants in the intervention group reported complete adherence to mask use recommendations, and 47% reported predominant adherence. At the end of the study period, 1.8% of participants in the intervention group and 2.1% of participants in the control group had evidence of SARS-CoV-2 infection as determined through RT-PCR or antibody testing. Overall, the relative odds of COVID-19 infection was 18% lower among participants among participants in the intervention group (OR 0.54-1.23). In sensitivity analyses, intervention group participants who reported insufficient compliance (7%) with mask use recommendations were excluded, but results were similar to the primary intent-to-treat analysis.

    Study strengths

    he authors randomized participants to receive recommendations for face mask use in attempt to strengthen causal inferences of any observed associations between use of surgical masks and COVID-19 infections. The authors also simulated data using multiple imputations to measure the impact of lost-to-follow-up (19%) on observed outcomes.

    Limitations

    Ascertainment of adherence to face mask recommendations in the intervention group through a single self-reported categorical measure (full compliance, predominant compliance, or non-adherence) is subject to misclassification, which likely introduced error into the observed associations. Low adherence to face mask recommendations in the intervention arm, with fewer than half of participants reporting complete compliance, suggests observed non-significant differences in COVID-19 infections between study arms is an artifact of poor intervention compliance and limited study power to detect significant difference between arms rather than face mask ineffectiveness in preventing COVID-19. The study also did not assess indirect benefits of face mask use as source control. Lastly, specimen self-collection among participants and self-reporting of antibody and antigen (i.e., PCR) testing results may have been prone to error.

    Value added

    This study is among the first to use a randomized design to assess whether surgical masks reduce COVID-19 susceptibility among wearers in a setting where mask use is limited.