CDC Report: SARS-CoV-2 transmission to masked and unmasked close contacts of university students with COVID-19.

SARS-CoV-2 Transmission to Masked and Unmasked Close Contacts of University Students with COVID-19 — St. Louis, Missouri, January–May 2021 – CDC Morbidity and Mortality Weekly Report

Commentary on Twitter

?work. MMWR: Unmasked exposure increased odds of COVID by 5 times! (aOR = 4.9; 95% confidence interval [CI] = 1.4–31.1) compared to exposures where both wore masks. University student study. Jan-May 2021. 4.8% fully vaccinated https://t.co/F4vQ6YT2Co

— Eli Perencevich, MD MS? ? (@eliowa) September 9, 2021