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Soumya

10 Feb, 9 tweets, 2 min read

The CDC is updating its mask guidance today to recommend new ways to make masks fit more tightly, including double-masking, knotting the ear loops or using a moldable nose wire. This is based on new science released today.

CDC researchers conducted an experiment in which they simulated aerosolized COVID-19 transmission between two people, and found that exposure was reduced by more than 95% when both people were wearing a cloth mask over a medical procedure mask.

"Masks work, and work best when they have a good fit and are worn correctly," says CDC director Dr. Rochelle Walensky.

The benefits are clear: In the CDC study, a medical procedure mask alone blocked 42% of particles from a simulated cough, while a cloth mask alone blocked 44%. A cloth mask covering a medical procedure mask blocked 92.5% of the cough particles.

And when both people were wearing fitted double masks, the receiver's exposure was reduced by 96%. When they were both wearing knotted and tucked masks, same thing -- 96% reduction.

from the CDC

the CDC study: cdc.gov/mmwr/volumes/7…

Here is the new CDC mask guidance, based on this new research: cdc.gov/coronavirus/20…

interestingly, officials are asking that people not combine a KN95 mask with any other mask. they also ask that people not combine two disposable masks, as they are not designed to fit tightly and wearing them on top of each other will not improve the fit.

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More from @skarlamangla

Soumya

@skarlamangla

11 Feb

So the CDC changed its masking guidance yesterday to recommend tighter-fitting masks as well as double masks. But they specifically warned against layering KN95s, which surprised me given how common that combo has become

This is how they explained it when I followed-up:

KN95s and N95s work very well on their own and adding masks on top or underneath could "affect how well they fit the face and decrease their effectiveness" and also make them hard to breathe through and uncomfortable, officials say.

"Masks that are not comfortable may not be worn by people as long as they are needed. It's important for consumers to find a mask that fits well but that also is comfortable enough that they can wear it for prolonged periods, if needed," reads a CDC statement sent to me.

Read 7 tweets

Soumya

@skarlamangla

10 Feb

The status of COVID variants in California:

-159 cases of the B117 UK variant
-1,203 cases of West Coast variant
-no cases of P1 variant, believed to have emerged in Brazil
-two cases of the South African B1351 variant -- one in Alameda and one in Santa Clara County

What we know about these variants:

-the B117 variant is believed to be about 50% more infectious. it's prevalence in the US is doubling every week
-research on the B1351 variant suggests it may make some vaccines less effective. it's an issue to keep an eye on

Some more details about B1351 in California:

In the Santa Clara County case, the person infected returned from international travel in mid-January and began experiencing symptoms several days later.

Read 4 tweets

Soumya

@skarlamangla

10 Feb

LA County officials say that food and agriculture workers will become eligible for vaccination here in the next two to three weeks.

That sectors breaks down like this. About half a million people in this category in LA County.

LA County officials say that childcare and education workers will become eligible for vaccination within the next two to three weeks. There are nearly 700,000 people who qualify under this category in the county.

Read 5 tweets

Soumya

@skarlamangla

10 Feb

https://twitter.com/skarlamangla/status/1359544379262738432

How many people are wearing cloth masks on top of KN95s?

The CDC's new masking guidance recommends wearing a cloth mask over a disposable mask, but it asks that people NOT layer KN95s. KN95s are meant to be worn on their own, it says.

https://twitter.com/skarlamangla/status/1359544379262738432

I'm trying to find out more soon on why they're recommending this, but I'm wondering if it's because KN95s have a structure to them and if you put something on top it might flatten the mask, and reduce the tightness of the seal? Hopefully will know more soon.

This is from the CDC's new masking guidance: cdc.gov/coronavirus/20…

Read 5 tweets

Soumya

@skarlamangla

8 Feb

Officials say that there are now five confirmed cases of the B117 coronavirus variant -- often called the UK strain -- in LA County.

LA County public health director Barbar Ferrer: "I would just note: there's no way that we don't have a fair amount of variant circulating, a fair amount of mutated virus circulating. It's just a question of how much and does it become dominant."