Abraar Karan Profile picture
Feb 4 6 tweets 2 min read
**New CDC MMWR**

Those reporting consistent mask use in indoor public settings were significantly less likely to test positive for #covid19

The effect was greatest in those reporting consistent N95 mask use

cdc.gov/mmwr/volumes/7… Image
2/ The data in favor of using N95 respirators for shared air / public indoor spaces during surges will continue to grow. Those who are skeptics will eventually come around. But the time lag will result in many needless infections, hospitalizations and deaths. It already has.
3/ Limitations of studies are always important.

Authors mention: “First, this study did not account for other preventive behaviors that could influence risk for acquiring infection, including adherence to physical distancing recommendations”

So one confounder here…
4/ would be if those who were more likely to wear better masks were also less likely to be at higher risk indoor shared spaces like crowded bars versus those who reported wearing no mask.

Shared indoor spaces differ in terms of their risk of spread (ventilation, crowding etc)
5/ I think this explanation could account for some of the difference between mask/ no mask, but less so between the type of mask you were wearing (are people who wear N95 really that much more careful than surgical; are those wearing surgical much more than cloth?)
6/ And remember— many public health experts once argued that masks would increase risk taking (an argument they made for no masks), so my attempt to give one confounder here to explain away the effect is as a devils advocate

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More from @AbraarKaran

Feb 7
In our ⁦@JAMA_current⁩ piece, we lay out a few key reasons that hospital-based #covid19 transmission is likely underappreciated.

1/ few hospitals systematically test patients throughout and following their hospital stays. jamanetwork.com/journals/jama/…
2/ “Most hospitals only test patients for SARS-CoV-2 at the time of admission and therefore may miss some infections acquired after admission, especially because approximately 40% of SARS-CoV-2 infections are mild or asymptomatic and thus do not trigger repeat testing.”
3/ “Furthermore, hospital stays for many non–COVID-19–related conditions are short, so some infections will only develop after discharge and will be missed or misattributed to posthospital exposures”
Read 4 tweets
Feb 5
1/ The biggest confounder in this study was the possibility that those who were more likely to mask in 2021 were more likely to only be doing lower risk indoor activities vs those without masks who were more likely to be doing higher risk ones.

cdc.gov/mmwr/volumes/7…
2/ For example, it is possible that those who reported not wearing a mask indoors were also more likely to be eating indoors or drinking at bars indoors near others

while those reporting wearing masks indoor may have been shopping for essentials in less crowded settings
3/ Unfortunately, we don’t have that information (authors could run this analysis though)

We only know that those who reported always wearing a face mask were much less likely to test positive than those who reported never wearing a face mask
Read 10 tweets
Feb 1
Writing up a case report that makes clear that immunologic consequences of #covid19 even weeks after recovering can be devastating; it’s unbelievably frustrating how many people outside of medicine confidently assert that “you’ll be fine” when doctors cannot even assert this.
2/ Any doctor that has been regularly taking care of #covid19 cases over the past two years can tell you that what we have seen has surprised us. There is still so much we are learning. Ascribing to a strategy that allows for wide spread is irresponsible.
3/ I know that many folks are tired & over it. I am also tired as are many colleagues who still understand that reducing transmission and creating safer environments within which we work, learn & socialize is what we should be demanding of our leaders.
Read 4 tweets
Jan 15
1/ In the first few weeks of the pandemic, almost all of the patients in the emergency room were of minority communities who were never given the luxury of staying home. ‘Lockdowns’ or whatever version we had were not equity focused— most vulnerable were the usual victims.
2/ But blaming this on Fauci or other scientists is missing the reality that our minority communities have often been at the center of inequities long before Covid. ‘Lockdowns’ didn’t “create” these inequities. And many of the folks shitting on Fauci & ‘lockdown’ policies…
3/ now seem to be jumping on the bandwagon as if their biggest concern is/was minority or impoverished communities. The worst part of these ill-faith arguments is that ‘focused protections’ essentially protects old people & allows young people- which includes frontline workers
Read 5 tweets
Jan 12
There is a lot that went wrong with face masks from day 1– we went from don’t wear them, to wear them, to double mask, to no mask, & now possibly CDC coming around to high filtration masks.

I lay out 4 lessons we can learn from this in @bmj_latest

bmj.com/content/376/bm…
2/ Acknowledge uncertainty— definitive statements about masks not working in the beginning were costly & based on lack of knowledge/evidence but were presented as if CDC was certain masks weren’t needed. They were wrong & then had to backpedal on it
3/ Precautionary principle — we should have assumed Covid19 was airborne and started with high filtration masks

3M had an FDA approved respirator for public health crises. We should have scaled this up (or something like it) for the public since day 1
Read 5 tweets
Jan 8
1/ All healthcare workers that are treating patients right now should be wearing N95 masks. Spread is like wildfire. We all risk bringing infections from the community into hospitals — from staff, visitors, & patients in whom initial screening is missing early incubation
2/ Hospitals are completely overwhelmed in terms of testing—it would be great to be testing staff and patients multiple times per week but this isn’t feasible when spread is happening this fast. Just testing those who need a test is taxing enough let alone regular screening
3/ Ventilation — some hospitals can increase ACH in certain rooms that have airborne capability (12 ACH) but for most these are limited ; cannot revamp entire system in the middle of a surge

cdc.gov/infectioncontr…
Read 5 tweets

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