Masks are Fantastic

Masks, in an ideal setting, produce an immense reduction in the amount of virus that passes through them, on the order of 98-99%.

https://pubmed.ncbi.nlm.nih.gov/33441205/

The major issues are people not wearing them properly and people wearing poor ones, which didn't matter much early in the pandemic, where surgical or even cloth masks sufficed.

https://pubmed.ncbi.nlm.nih.gov/32673300/

More infectious strains change the calculus because either a smaller number of virions is sufficient for infection or there are just more virions being expelled, and masks are a percentage reduction.

A population educated on how to do a proper fit test with an N95 (or KN95) mask should see a dramatic decrease in transmission even with Alpha or Delta, although preliminary data out of Israel, where masking is mandatory indoors and outdoors, indicates that compliance or proper masking is not comprehensive or that surgical masks might not be effective enough anymore.

Here is a great review study of many mask studies in different countries and settings with different kinds of masks.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8084286/

At least Alpha, and undoubtedly Delta, the sneeze machine, is better at evading masks than less infectious strains, so cloth is basically out. I'm not aware of any Delta-specific studies. We need data.

https://www.biorxiv.org/content/10.1101/2021.07.26.453518v1

It is unlikely that a strain could soon emerge that was so infectious that good masks worn well became ineffective. In early isolates, only 1% of S proteins were prepared for infection. In Alpha, it was around 50%, and in Delta, around 75%, so we're maxing out the infectivity gains that can be achieved that way. A big thing to watch for is SARS-CoV-2 breaking through the TMPRSS2 bottleneck somehow.

https://www.nature.com/articles/d41586-021-02039-y

Most people who do not comply with mask mandates are males and middle-aged adults.

https://www.biorxiv.org/content/10.1101/2021.02.25.432837v1

I would say that surgical masks remain very protective worn right, but N95 masks are substantially more effective. This is not because of pore size, but because it's way easier to get a clean seal with an N95 mask. All masks depend crucially on proper wear, so training is critical. They help most when everyone wears them because mask #1 reduces virus expelled by the donor and mask #2 reduces virus inhaled by the new host. Cloth is not effective enough to be worth it anymore.

The CDC has videos to help with wearing, as do others.

https://www.youtube.com/watch?v=dSvff0QljHQ
https://www.youtube.com/watch?v=CoSb-HJJ5tk

There are unlikely to be any studies published that consider Ct count specifically outside of the strains because it's definitionally included in infection rates, and I'm not aware of any studies that have attempted yet. Breaking things out by strain makes a lot more sense because that has a much higher correlation with infection rates, and it's just easier. Someone will probably do it eventually.

Alternatively, America could consider snap enacting Singapore's approach.

https://www.cnn.com/2021/08/18/asia/singapore-briton-jailed-mask-intl-hnk/index.html

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