"Neither surgical nor cotton masks effectively filtered SARS–CoV-2 during coughs by infected patients."
https://annals.org/aim/fullarticle/...sks-blocking-sars-cov-2-controlled-comparison
...
?
This “study” had an effective n=3. More like science project, not study level. And they didn’t even collect petri data on patient #4.
Let’s agree the necessary innoculum dose of virus to -> COVID is not known.
Firstly, what if all 4 patients were robust cough-ers, b/c that would affect viral plume w/ cough.
Secondly, the letter reported #1 coughing w/ a cotton mask lands 2.27log copies/ml virus on petri dish vs. 3.53. In #3 patient, it’s 1.42 vs. 2.52. So 36% and 44% reduction of viral load. So if a viral dose of 2.6 log copies/ml successfully causes an infection, then yes, a cloth mask works and is effective.
Also, the distance from mouth opening to petri dish was 20cm. Who stands that close these days? So if at 20cm, a cloth mask reduces viral cough load of 30-40%, and then extrapolate that to 6ft, then that might be good enough to prevent successful infecting dose.
And finally, virus was sometimes detected on the outer surface of the mask, but not inner. The authors argued about turbulent air jets.
OK, one then could counter: if masks result in a venturi effect, changing the dynamics of a cough, then everyone should wear masks -> b/c when you cough with a mask on, the virus particles’ forward travel is rerouted onto the mask instead of forward into the air.
Anyways, they need a larger sample size than essentially 3, with data for each patient, not this hodge podge measurements. Given that some COVID case series have +5k, this should achievable.
should have known THEY were keeping track 
.
