Thread by @AbraarKaran

One of the problems w/ CDC isolation guidelines is it hinges on many assumptions, some which may be clarified with more data tomorrow, and others which cannot be clarified or even really monitored/guaranteed by any means

1/

First assumption is that most people are barely transmitting after day 5. This might be true- but I haven't seen that data the way it was shown for transmission early on which helped to create the 10 day protocol

Esp need that data for people w/ Omicron specifically

2/

Second assumption is that people who are done isolating and feel better will actually wear a mask at all

Third assumption is that cloth masks or whatever people are using that are not high filtration actually have good source control (no good data saying this is true)

3/

At a time when we are surging and hospital systems are starting to feel that... we have to balance both how we can best reduce transmission w/ how we can actually keep a workforce up and running, esp for hospitals w/ serious constraints. I can appreciate this.

4/

I don't know if CDC becoming more lenient on isolation at the tail end of acute infection is really going to matter that much in terms of overall transmission--it might, it might not; from what we know, most transmission is happening before symptoms (although not all)

5/

So the fundamental problem of early asymptomatic spread really isn't affected much here. We will continue to have a lot-- A LOT-- of transmission either way until we solve that

We may have a more 'accessible' workforce w/ these protocols, but I fear we are seriously in trouble

I definitely think that there were ways to make this isolation revision much better, as many have already talked about (testing, better masks etc)

But more than that-- the communication around this seems to once again have been a huge mess! CDC should have anticipated this...

Another question... how many people were actually isolating- truly isolating- for 10 days? Maybe a lot, maybe not. Who knows.

But even more important (to me)- how many have actually been quarantining after exposure and testing?
I'll explain

I think for many, by the time they find out they are positive (that the sniffles weren't just allergies) and start 'isolation'-- they likely have already been transmitting for a couple of days or more.

We have failed to have a real quarantine system since day 1 of #Covid19

One big caveat here- & I hope that the CDC addresses this tomorrow — to what degree has vaccination shifted the peak viral load relative to symptom onset & how much does this change between Delta & Omicron

would be great to have some lab data on this