Thread by @JamesCasciano4

1) Oct 2019 World Health Organization published guidance stating mask use by the general public during a pandemic was only conditionally recommended. (See page 20 of apps.who.int/iris/bitstream…

2) “Face masks worn by asymptomatic people are conditionally recommended to reduce transmission in the community. Although there is no evidence that this is effective in reducing transmission, there is mechanistic plausibility for the potential effectiveness...."

3) All IH’s should understand the science, do the research, present both sides objectively and be clear in explaining technical versus policy reasons and decisions. That is the role of all IH’s and public health practitioners.

4) The most complete listing of the mask literature I’ve found is from the Association of American Physicians and Surgeons: aapsonline.org/mask-facts/.

5) A cloth mask has little utility from a technical standpoint. It may have a role in a control strategy to remind people to stay arm’s length away, to stay home when sick, and to wash hands. Those are the things that we know historically do work for cold/flu like diseases.

6) The technical literature, where it finds benefit from mask use consistently qualifies the finding by saying when combined with other measures like distancing. IH’s should be able to confidently say.....

7) ......that cloth masks are not an approved personal protective device, that the medical and IH literature has limited and qualified evidence of any benefit and therefore the use is a policy decision, not a technical or scientific one.