Impact of community mask mandates on SARS-CoV-2 transmission in Ontario after adjustment for differential testing by age and sex | PNAS Nexus | Oxford Academic https://academic.oup.com/pnasnexus/article/3/2/pgae065/7606553 “The prevented fraction associated with #MaskMandates was 46% (95% CI 41–51%), with 290,000 clinical #cases, 3,008 #deaths, and loss of 29,038 quality-adjusted life years (#QALY) averted from 2020 June to December, representing $CDN 610 million in economic wealth. (1/2)