[ExI] the CDC's weird recommendation on masks

[Stuart LaForge]

I don't understand this recommendation from the CDC for the public to  
NOT wear masks for COVID-19 prophylaxis. Is it based on any evidence  
or data? Or is it just because the supply shortage for healthcare  
workers? Maybe N-95 respirators are overkill for the general public  
that is not regularly face to face with infected patients or entering  
rooms with several patients. But why shouldn't somebody at risk not  
wear a surgical mask on the subway or bus?

Yes, the virus is small enough to go through the pores of a surgical  
mask but it will certainly stop many of the larger aerosol droplets.  
 From the average cough or sneeze from three to six feet away. In fact  
according to this review of the literature, simple disposable surgical  
masks ARE effective in protecting the wearer according to 6 out of 7  
studies. This is stronger than the evidence for the efficacy of hand  
washing which was also protective but in only 4 out 7 studies.

https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD006207.pub4/full

"These data suggest that wearing a surgical mask or a N95 mask is the  
measure with the most consistent and comprehensive supportive  
evidence. Seven out of eight studies included masks as a measure in  
their study and six out of seven of these studies found masks to be  
statistically significant in multivariable analysis. Handwashing was  
also included in seven of the studies with four studies showing  
handwashing to be statistically significant in multivariable analysis.  
All other measures were shown to be statistically significant in  
multivariable analysis on only one or two occasions."

What is going on here? Does the CDC just think everybody is too stupid  
to properly use a face mask properly? I have in the past been coughed  
on in public to my great annoyance so it certainly is a realistic  
risk. My professional opinion as a microbiologist is that at risk  
people should absolutely wear a mask in crowded conditions and safety  
glasses or goggles as well. And if you can't buy any because they are  
sold out or too expensive due to price gouging, then you should make  
your own:

https://www.youtube.com/watch?v=cZGU2vWHKC8

In my opinion ANY barrier to the aerosol from sick people is better  
than no barrier. Any insights from the other list members with biomed  
experience?

Stuart LaForge