I’ll answer since I’m a statistician. The paper was what is called a meta-analysis, that is, a study of studies. I personally think that meta-analyses are overrated; I believe in the smorgasbord theory where you put a lot of crap on a table and call it a smorgasbord. As is typically the case, the 14 studies investigated are of differing quality.
The report says
“Although mechanistic studies support the potential effect of hand hygiene or face masks, evidence from 14 randomized controlled trials of these measures did not support a substantial effect on transmission of laboratory-confirmed influenza.”
The key word here is “substantial”; I don’t think that anyone would expect a “substantial effect” since relatively few people have the virus and person to person contact is severely restricted. Also the studies were on the flu which evidently is much less contagious.
The report also says “Some studies reported being under-powered because of limited sample size, and low adherence to hand hygiene interventions was observed in some studies.” Under-powered means that the studies had too few subjects to detect small effects and one would expect the effect here to be small.
It should be noted that the purpose of face masks is not to protect the person wearing it but to protect others if you should be carrying the virus. I think that what is important is that business employees wear masks since they are in contact with many people. Although the chance of my being positive is essentially zero, I did wear one when I went to Harris Teeter, just to be patriotic.
I don’t think that we are at serious risk in North Carolina; the latest figures are
May 13
Laboratory-Confirmed Cases – 15,816
Deaths – 597
Completed Tests – 210,457
Currently Hospitalized – 521
US – 1,371,395
Death – 82,461
Elliot M. Cramer
PO 428
Chapel Hill, NC 27514
919-942-2503
Professor Emeritus
Department of Psychology
University of North Carolina at Chapel Hill
Websites
http://www.ourpaws.info
http://www.friendsofocas.org
Date: Thu, 14 May 2020 10:19:59 -0400
From: Elliot Cramer
Subject: Gene’s question on evidence for masks