Public use of face masks for limiting the spread of the COVID-19 pandemic is controversial, though increasingly recommended. The impact of this intervention on morbidity and mortality is not well understood. This study developed a compartmental model for assessing the community-wide impact of mask use by the general, asymptomatic public.
The authors used data from New York and Washington and adapted a previously developed SEIR model framework for transmission dynamics to explore the potential community-wide impact of public use of face masks, of varying efficacy and compliance, on the transmission dynamics and control of COVID-19.
Their findings suggest that broad adoption of even relatively ineffective face masks may meaningfully reduce community transmission of COVID-19 and decrease peak hospitalizations and deaths.
Specifically, their models suggest that mask use decreases the effective transmission rate in nearly linear proportion to the product of mask effectiveness and coverage rate. Their findings suggest that masks are useful with respect to both preventing illness in healthy persons and preventing asymptomatic transmission.
Under hypothetical mask adoption scenarios, the models suggest that immediate near universal (80%) adoption of moderately (50%) effective masks could prevent on the order of 17–45% of projected deaths over two months in New York, while decreasing the peak daily death rate by 34–58%, absent other changes in epidemic dynamics. In Washington, where baseline transmission is much less intense, 80% adoption of weaker masks (20% effective) could reduce mortality by 24–65% (and peak deaths 15–69%), compared to 2–9% mortality reduction in New York (peak death reduction 9–18%).
They conclude that the use of face masks by the general public is potentially of high value in curtailing community transmission and the burden of the pandemic. The community-wide benefits are likely to be greatest when face masks are used in conjunction with other non-pharmaceutical practices (such as social-distancing), and when adoption is nearly universal (nation-wide) and compliance is high.