Evaluation of different types of face masks to limit the spread of SARS-CoV-2: a modeling study

• Type of Material: Article
• Authors: Brian M Gurbaxani, Georgia Institute of Technology; Andrew Hill, Emory University; Prabasaj Paul, CDC COVID-19 Response Team, Atlanta; Pragati V Prasad, CDC COVID-19 Response Team, Atlanta; Rachel B Slayton, CDC COVID-19 Response Team, Atlanta
• Language: English
• Date: 2022-12-01
• Publisher: Springer Nature Limited
• Publication Version: Final Published Version
• Copyright Statement: © This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply 2022
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1038/s41598-022-11934-x
• Title of Journal or Parent Work: Scientific Reports
• Volume: 12
• Issue: 1
• Start Page: 8630
• End Page: 8630
• Grant/Funding Information: All authors are employees of the CDC—no external funding was needed.
• Keywords: United States; Textiles; SARS-CoV-2; COVID-19; Humans; Masks
• Research Categories: Engineering, Electronics and Electrical; Biology, Biostatistics; Engineering, System Science

Abstract

We expanded a published mathematical model of SARS-CoV-2 transmission with complex, age-structured transmission and with laboratory-derived source and wearer protection efficacy estimates for a variety of face masks to estimate their impact on COVID-19 incidence and related mortality in the United States. The model was also improved to allow realistic age-structured transmission with a pre-specified R0 of transmission, and to include more compartments and parameters, e.g. for groups such as detected and undetected asymptomatic infectious cases who mask up at different rates. When masks are used at typically-observed population rates of 80% for those ≥ 65 years and 60% for those < 65 years, face masks are associated with 69% (cloth) to 78% (medical procedure mask) reductions in cumulative COVID-19 infections and 82% (cloth) to 87% (medical procedure mask) reductions in related deaths over a 6-month timeline in the model, assuming a basic reproductive number of 2.5. If cloth or medical procedure masks’ source control and wearer protection efficacies are boosted about 30% each to 84% and 60% by cloth over medical procedure masking, fitters, or braces, the COVID-19 basic reproductive number of 2.5 could be reduced to an effective reproductive number ≤ 1.0, and from 6.0 to 2.3 for a variant of concern similar to delta (B.1.617.2). For variants of concern similar to omicron (B.1.1.529) or the sub-lineage BA.2, modeled reductions in effective reproduction number due to similar high quality, high prevalence mask wearing is more modest (to 3.9 and 5.0 from an R0 = 10.0 and 13.0, respectively). None-the-less, the ratio of incident risk for masked vs. non-masked populations still shows a benefit of wearing masks even with the higher R0 variants.