Association of County-Wide Mask Ordinances with Reductions in Daily CoVID-19 Incident Case Growth in a Midwestern Region Over 12 Weeks

Abstract

Importance: This study assessed the longitudinal impact of new COVID-19 cases when a mask ordinance was implemented in 2 of a 5-county Midwestern U.S. metropolitan region over a 3-month period of time. Reduction in case growth was significant and reduced infection inequities by race and population density. Objective: The objective of this study was to assess the impact that a mandatory mask wearing requirement had on the rate of COVID-19 infections by comparing counties with a mandatory policy with those neighboring counties without a mandatory masking policy. Design: This was a quasi-experimental longitudinal study conducted over the period of June 12-September 25, 2020. Setting: This study was a population-based study. Data were abstracted from local health department reports of COVID-19 cases. Participants: Raw cases reported to the county health departments and abstracted for this study; census-level data were synthesized to address county-level population, income and race. Intervention(s) (for clinical trials) or Exposure(s) (for observational studies): The essential features of this intervention was an instituted mask mandate that occurred in St. Louis City and St. Louis County over a 12 week period. Main Outcome(s) and Measure(s): The primary study outcome measurement was daily COVID-19 infection growth rate. The mask mandate was hypothesized to lower daily infection growth rate. Results: Over the 15-week period, the average daily percent growth of reported COVID-19 cases across all five counties was 1.81% (sd 1.62%). The average daily percent growth in incident COVID-19 cases was similar between M+ and M- counties in the 3 weeks prior to implementation of mandatory mask policies (0.90% [sd 0.68] vs. 1.27% [sd 1.23%], respectively, p=0.269). Crude modeling with a difference-in-difference indicator showed that after 3 weeks of mask mandate implementation, M+ counties had a daily percent COVID-19 growth rate that was 1.32 times lower, or a 32% decrease. At 12 weeks post-mask policy implementation, the average daily COVID-19 case growth among M- was 2.42% (sd 1.92), and was significantly higher than the average daily COVID case growth among M+ counties (1.36% (sd 0.96%)) (p<0.001). A significant negative association was identified among counties between percent growth of COVID-19 cases and percent racial minorities per county (p<0.001), as well as population density (p<0.001). Conclusions and Relevance: These data demonstrate that county-level mask mandates were associated with significantly lower incident COVID-19 case growth over time, compared to neighboring counties that did not implement a mask mandate. The results highlight the swiftness of how a mask ordinance can impact the trajectory of infection rate growth. Another notable finding was that following implementation of mask mandates, the disparity of infection rate by race and population density was no longer significant, suggesting that regional-level policies can not only slow the spread of COVID-19, but simultaneously create more equal environment.

Modeling the Transmission of COVID-19: Impact of Mitigation Strategies in Prekindergarten-Grade 12 Public Schools, United States, 2021

“…To assess the impact of mitigation strategies on reducing in-school transmission, we created 2 scenarios that reflect "low" and "high" levels of impact resulting from the combined implementation of 4 individual mitigation strategies: mask wearing, [20][21][22][23][24][25] cleaning and disinfection, 22 hand hygiene, 22,26 and social distancing 26 (Table 2 and Supplemental Digital Content Appendix A-Table 2 available at http: //links.lww.com/JPHMP/A813). Three factors were considered for calculating the combined effectiveness of these mitigation strategies on SARS-CoV-2 transmission: efficacy ¶ of individual mitigation strategies, compliance (over an entire school term), and how mitigation strategies interact.…”

“…Three factors were considered for calculating the combined effectiveness of these mitigation strategies on SARS-CoV-2 transmission: efficacy ¶ of individual mitigation strategies, compliance (over an entire school term), and how mitigation strategies interact. Estimates of efficacy for each mitigation strategy were based on published data [20][21][22][23][24][25][26] ; the degrees of compliance were assumed as no data about adherence with individual mitigation strategies in school settings are available. Finally, we assumed a nonlinear effect of simultaneous implementation of individual mitigation strategies, such that each additional mitigation strategy provided a decreasing marginal impact on reducing SARS-CoV-2 transmission (Supplemental Digital Content Appendix A-Figure 1 available at http://links.lww.…”

Use of Face Masks in India During COVID-19 : An Exploration of the Behavioral Tendencies of Mask Users

“…When it comes to the general population, a higher rate of compliance (Betsch et al, 2020) to the mask usage guidelines and mandatory mask policy, resulted in decreasing number of Covid positive cases (Shacham et al, 2020). There might be a difference in ideal and actual mask usage depending upon people's attitudes and beliefs especially during the early response to pandemics (Timpka & Nyce, 2021).…”

Local, state and federal face mask mandates during the COVID-19 pandemic

“…17 Similar trends comparing counties with and without public face mask requirements have also been reported in Missouri. 18 Many hospitals and healthcare systems are currently operating at crisis capacity, and their inpatient surge capacity plans are not meeting the widening gap. Temporary "overflow facilities" are being erected, adults are overflowing into children's hospitals, and hospital staffing shortages are not being met.…”