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R. Soc. Interface."],"published-print":{"date-parts":[[2022,5]]},"abstract":"<jats:p>Face masks do not completely prevent transmission of respiratory infections, but masked individuals are likely to inhale fewer infectious particles. If smaller infectious doses tend to yield milder infections, yet ultimately induce similar levels of immunity, then masking could reduce the prevalence of severe disease even if the total number of infections is unaffected. It has been suggested that this effect of masking is analogous to the pre-vaccination practice of variolation for smallpox, whereby susceptible individuals were intentionally infected with small doses of live virus (and often acquired immunity without severe disease). We present a simple epidemiological model in which mask-induced variolation causes milder infections, potentially with lower transmission rate and\/or different duration. We derive relationships between the effectiveness of mask-induced variolation and important epidemiological metrics (the basic reproduction number and initial epidemic growth rate, and the peak prevalence, attack rate and equilibrium prevalence of severe infections). We illustrate our results using parameter estimates for the original SARS-CoV-2 wild-type virus, as well as the Alpha, Delta and Omicron variants. Our results suggest that if variolation is a genuine side-effect of masking, then the importance of face masks as a tool for reducing healthcare burdens from COVID-19 may be under-appreciated.<\/jats:p>","DOI":"10.1098\/rsif.2021.0781","type":"journal-article","created":{"date-parts":[[2022,5,4]],"date-time":"2022-05-04T07:07:47Z","timestamp":1651648067000},"update-policy":"https:\/\/doi.org\/10.1098\/crossmark-policy","source":"Crossref","is-referenced-by-count":15,"title":["Face masking and COVID-19: potential effects of variolation on transmission dynamics"],"prefix":"10.1098","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1903-4393","authenticated-orcid":true,"given":"Zachary","family":"Levine","sequence":"first","affiliation":[{"name":"Department of Mathematics and Statistics, McMaster University, Hamilton, Canada L8S 4K1"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7562-1341","authenticated-orcid":true,"given":"David J. D.","family":"Earn","sequence":"additional","affiliation":[{"name":"Department of Mathematics and Statistics, McMaster University, Hamilton, Canada L8S 4K1"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"175","published-online":{"date-parts":[[2022,5,4]]},"reference":[{"key":"e_1_3_6_2_2","unstructured":"Dr Vivek Murthy U S Surgeon General. 2020 The best way to protect yourself and your community is with everyday preventive actions like staying home when you are sick and washing hands with soap and water to help slow the spread of respiratory illness. Get your FluShot- fewer flu patients = more resources for COVID19. (accessed 15 July 2021). See https:\/\/twitter.com\/Surgeon_General\/status\/1233726563881029632."},{"key":"e_1_3_6_3_2","unstructured":"World Health Organization. 2020 Advice on the use of masks in the context of COVID-19: interim guidance 6 April 2020. (accessed 15 July 2021). 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