Thread by @DrLaurenWilson

On Tuesday @DPHHSMT wrote emergency orders citing "science" that masks don't work: a smattering of sources such as popular press, letters to the editor, articles they misread and - yes - tweets.

Might be time for a giant thread on the evidence behind masking? LET'S GOOOOO.

And by GIANT, I mean GIANT, because, well, there's a lot of evidence.

This is necessary context for when people throw out one-off colorful graphs of questionable provenance and saying, SEE?!? SEE?!?

I can't respond to all of that, if I had a zillion hours in the day.

Remember: Scientific consensus is built on more than a cut-and-paste list of articles. Trust experts who review ALL the evidence as it comes out, and tell you >>90% aligns. (Climate, anyone?)

Luckily, @KatieMLoveland dismantles the @DPHHSMT list here 👇

https://twitter.com/KatieMLoveland/status/1432831435736424452?s=19

**Disclaimer**

Masks are only part of a layered strategy to stop COVID spread, including vaccination, distancing, ventilation, handwashing, testing, quarantine & isolation, testing & tracing.... ALL the things.

Some of which we do OK at in the U.S., some of which we suck at.

But for myriad and sometimes obscure reasons, masks and vaccines have emerged as flashpoints for misinformation and, well, lots of feelings.

Do I want to be debating about masks all the time? I sure don't.

So, the necessary but long MASKS WORK thread:

1/lots

First. An NIH-funded Duke collaborative found low transmission in North Carolina schools with masking, even if distancing was not possible.

(And, who knew? NC kids sit 3 to a bus seat. Friendly down there!)

abcsciencecollaborative.org/the-abcs-of-no…

A nice review of 7 studies showing positive effects of masking in different settings, from Beijing to Bangkok to a (!) hair salon in Missouri.
jamanetwork.com/journals/jama/…

Bigger: An enormous narrative review of >140 studies on masking in COVID, masking in other respiratory illnesses, and mechanisms of action.

(You're WELCOME for not listing all 140 individually)

pnas.org/content/118/4/…

"But where is my RCT?!?"

BAM, here's one. Cluster randomized. 300k people. Villages with higher masking rates = less COVID. Surgical masks were better, and the effect was seen even with less than perfect compliance.

poverty-action.org/publication/im…

If you're bringing the earlier "negative Dutch trial":

Accompanying editorial: “Results of this trial should motivate widespread mask wearing to protect our communities and thereby ourselves while we await more definitive evidence during this pandemic.”
factcheck.org/2020/11/danish…

Also related, this great thread about how randomizing individuals isn't a good study design for masking

https://twitter.com/trishgreenhalgh/status/1414295704357543942?s=19

Bonus for those asking for blinding. Um. How should that work? Like, am I wearing a mask or aren't I?

Now here's a look at all the existing (admittedly limited, even searching English/German/French language) studies about harm from masks, concluding that none was found.

ncbi.nlm.nih.gov/pmc/articles/P…

Here's a lovely one for the OK-masks-work-but-mandates-don't crowd.

healthaffairs.org/doi/10.1377/hl…

And another of those, just looking at Kansas counties who had mask mandates versus those that didn't.

Spoiler alert: You guessed it
😷 = less 🤒

jamanetwork.com/journals/jaman…

Medical people are nerds and get suuuper excited about meta-analyses. It's what you get when you throw together data from many, many studies.

Suuuuuuper excited.

That little diamond thing left of the line = masks have a significant effect.

thelancet.com/journals/lance…

Oh, here's another on schools. Transmission rare with masks.

sciencedaily.com/releases/2021/…

Getting a bit repetitive, now.

Transmission rare in schools with masks and mitigation. Also suggests a stoplight system for school measures based on community transmission (which is high in Montana).

mcri.edu.au/sites/default/…

Do kids have trouble recognizing emotions in a masked face?

Spoiler alert: Nope

pubmed.ncbi.nlm.nih.gov/22892280/

Let's be honest, we don't want the kids sick, but we REALLY don't want them to kill their parents or grandparents. Here looking at schools that enacted multiple mitigation measures, household transmission of SARS-CoV-2 is lower.

science.org/doi/full/10.11…

Ooh, another meta-analysis, showing a 60% reduction in transmission overall (70% in health care workers).

ncbi.nlm.nih.gov/pmc/articles/P…

Tired? Just getting started?

Me, I'm tired. So I will get lazy and screenshot a compiled list of additional evidence, and you let me know if you want more hot takes on it.

Oh, hey, wait, here's a second page.

Yeah it just keeps coming. Page 3.

(And just think, the people making CDC guidelines read ALL of these!)

And /FIN, for now.

Can you find weaknesses in any study? Sure. But for masks, ultimately: there is a plausible mechanism, a fairly consistent effect size, and the vast vast majority of the studies agree.

Masks are also simple, cheap, and LESS restrictive than other tools.

So ultimately you can, you know, trust the experts on this one.

Will universal masks be forever? No. But at times of high community transmission (i.e. now) they assist to keep kids with their friends, in school.

I look forward to when we can stop talking about them so much.