More evidence that masks work (longish - but the conclusion notes an enormous saving)
An evidence review of face masks against COVID-19
Jeremy Howarda,b,1, Austin Huangc, Zhiyuan Lid, Zeynep Tufekcie, Vladimir Zdimalf,
Helene-Mari van der Westhuizeng,h, Arne von Delfth,i, Amy Pricej, Lex Fridmank, Lei-Han Tangl,m, Viola Tangn, Gregory L. Watsono, Christina E. Baxp, Reshama Shaikhq, Frederik Questierr, Danny Hernandezs, Larry F. Chuj, Christina M. Ramirezo, and Anne W. Rimoint
Edited by Lauren Ancel Meyers, The University of Texas at Austin, Austin, TX, and accepted by Editorial Board Member Nils C. Stenseth December 5, 2020 (received for review July 13, 2020)
The science around the use of masks by the public to impede COVID-19 transmission is advancing rapidly. In this narrative review, we develop an analytical framework to examine mask usage, synthesizing the relevant literature to inform multiple areas: population impact, transmission characteristics, source control, wearer protection, sociological considerations, and implementation considerations. A primary route of transmission of COVID-19 is via respiratory particles, and it is known to be transmissible from presymp- tomatic, paucisymptomatic, and asymptomatic individuals. Reducing disease spread requires two things: limiting contacts of infected individuals via physical distancing and other measures and reducing the transmission probability per contact. The preponderance of evidence indicates that mask wearing reduces transmissibility per contact by reducing transmission of infected respiratory particles in both laboratory and clinical contexts. Public mask wearing is most effective at reducing spread of the virus when compliance is high. Given the current shortages of medical masks, we recommend the adoption of public cloth mask wearing, as an effective form of source control, in conjunction with existing hygiene, distancing, and contact tracing strategies. Because many respiratory particles become smaller due to evaporation, we recommend increasing focus on a previously overlooked aspect of mask usage: mask wearing by infectious people (“source control”) with benefits at the population level, rather than only mask wearing by suscep- tible people, such as health care workers, with focus on individual outcomes. We recommend that public officials and governments strongly encourage the use of widespread face masks in public, including the use of appropriate regulation.
a tip of the hat to Roland
and the need for a national mask initiative Biden has stated this although details other than a 100 day minimal length haven't been stated as far as I can tell.
a tip of the hat to Sukie