Thread by @ahandvanish

This seems to be the leaked data the CDC used to change the mask mandate this week:

context-cdn.washingtonpost.com/notes/prod/def…

There's a lot to dig in here but a few things that jump out about Delta particularly:

1/

Delta objectively spreads faster than the original COVID strain. The original strain was less transmissible than polio & smallpox; Delta is more transmissible than those as well as Ebola, MERS, SARS, & the Spanish Flu.

Delta is *as* transmissible as chicken pox.

2/

Delta is associated with a higher viral load and longer duration of shedding.

3/

A big one: breakthrough cases from Delta may be as transmissible as unvaccinated cases.

4/

Data suggesting that Delta may cause more severe disease.

5/

Some preliminary data show that the vaccines may be less protective against non-hospitalized symptomatic infections of Delta. (This is bad news & will likely mean more #LongCOVID cases.)

6/

From the CDC's model, Delta cannot be controlled without universal masking!

This seems to be where their change in policy is coming from.

7/

Finally, a list of much needed changes to public communication from the CDC, including to "acknowledge the war has changed". Delta is different & concerning, and vaccinated individuals still are at risk.

8/

In short: we are not through the woods, and the CDC's de-masking recommendations came too early.

Everyone should return to masking & should be aware that being vaccinated can't be the sole means of protection on its own, but instead used alongside other precautions.

9/

Vaccinated individuals are less likely to be hospitalized & die, but with Delta they risk transmitting COVID to others, including unvaccinated kids (who seem to be at greater risk from Delta).

They also remain at risk of contracting #LongCOVID from breakthrough infections.

10/

A very relevant thread to end on:

https://twitter.com/erinbiba/status/1420908024261140481

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