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Dr. Abraar Karan Profile picture
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5 Oct, 4 tweets, 2 min read
NEW: CDC has now *officially* updated their #covid19 transmission guidelines acknowledging that the virus can hang around in the air for several mins or more— & it can transmit beyond 6 feet in scenarios with poor ventilation that are enclosed.

washingtonpost.com/health/2020/10…
2/ Several outbreak studies have suggested this for months—& yet it is only now that this is being officially acknowledged

This is one of my personal biggest issues w/ our epidemic response— despite having some data, we don’t move to act when benefits of doing so outweigh costs
3/ Our communications to the public have focused almost exclusively on droplet-based spread— “6 feet apart” and “wear a mask”.

6 feet apart is NOT always sufficient!

And cloth masks are NOT designed to stop aerosols that hang around in the air.
4/ This is why many of us have focused on strategies such as 3 Cs from Japan— avoid prolonged close contact, closed spaces, and crowds. This can help stop super spreading events, a number of which are why we believe the virus is airborne in certain circumstances.

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More from @AbraarKaran

Dr. Abraar Karan Profile picture
5 Oct
1/ The CDC guidelines that are finally acknowledging aerosols-- particles that hang around in the air/travel more than 6 feet--playing a role in #covid19 transmission is *not new*

Within the public health community, it was clear that they did play *some* role, unclear how big
2/ But even now, what % of transmission is happening via respiratory route that is *not* from droplets is unclear.

What we suspect is that in situations w/ poor ventilation, crowds, & sustained contact, aerosols (in addition to droplets) can lead to transmission of the #covid19.
3/ This has a number of implications for public health--especially as it relates to what level of minimal protection (type of mask) is needed in different situations.

As healthcare workers, we are using N95 masks if #covid19 is suspected or confirmed.
Read 5 tweets
Dr. Abraar Karan Profile picture
4 Oct
1/ Reports that Trump received #dexamethasone— a steroid that should only be used on patients who require oxygen or are critically ill with #covid19. This was proven to reduce mortality in the RECOVERY trial published in @NEJM earlier this year.

nejm.org/doi/full/10.10…
2/ But, they found no mortality benefit in patients that were not on supplemental oxygen or ventilators.

In fact, those patients actually had a slightly higher mortality rate, although not statistically significant.
3/ The basic premise is that once you are sick enough, your immune response is what needs to be tempered/ what may end up killing you rather than the virus itself. So steroids can help control this.

Speculating what this could mean...
Read 4 tweets
Dr. Abraar Karan Profile picture
1 Oct
Thread
1/ Covid alert NY--> an app that uses bluetooth technology to help notify people if they were exposed within 6 feet to someone who tests positive for #covid19 w/o storing any personal information & without tracking location.

Important effort here
coronavirus.health.ny.gov/covid-alert-ny
2/ Closing the exposure to quarantine/isolation window is critical to stop spread

Recent report from NC--> specimen collection to contact notification median of *6 days*

A number of cases did not report *any* contacts, & many could not be reached at all
cdc.gov/mmwr/volumes/6…
3/ If enough people opt-in to a bluetooth based exposure notification system, we can re-direct resources appropriately, particularly around who to test; also increase *speed*

Exposure notification needs to take time spent/location of exposure into account as well.
Read 8 tweets
Dr. Abraar Karan Profile picture
25 Sep
Many close colleagues & friends were impacted by this; & many of our incredible hospital epidemiologists are hard at work.

But, I do think that it is critically important that all hospitals provide regular #covid19 testing for employees, especially given asymptomatic spread.
2/ By the nature of hospital work-- crowded together in small rooms for much of the day-- it becomes virtually impossible to prevent this type of spread without regular testing.

And, given aerosol contribution is most relevant in closed, poorly ventilated rooms...
3/ ...surgical masks alone are not always sufficient, for individual protection, or for source control.

We need to protect our healthcare workers. This is one of the applications in which rapid antigen testing could have big implications- ensuring no infectious worker comes in.
Read 5 tweets
Dr. Abraar Karan Profile picture
22 Sep
1/ Contact tracing efforts in 2 counties in North Carolina described in today's MMWR

-->High % of #covid19 cases reported having "no contacts" or their contacts couldn't be reached

-->median time from sample collection to calling a case was 6 days

cdc.gov/mmwr/volumes/6…
2/ Authors cited concerns that cases may not refer contacts in fear they would risk loss of work or other economic consequences

They also cited the need for more rapport building.

Different states have had different experiences of course
3/ Data from Maryland & New Jersey indicated 50-52% of index cases reported having "no contacts" either

Clear issues- if median time from receiving a sample for testing to contacting a positive case is 6 days, your testing-isolation window is far too wide/needs to be much faster
Read 5 tweets
Dr. Abraar Karan Profile picture
21 Sep
1/ CDC putting aerosols under “common routes of spread” of #covid19 is a significant shift.

We have been saying “wear a mask” and “6 feet apart” for months.

Cloth masks are not designed to block aerosols. And 6 feet apart may be insufficient, esp indoors w/ poor ventilation.
2/ Many experts have understood for a long time now that both droplets and aerosols play a role in spread.

But the big public communications campaigns have *largely focused on droplets only*

This is the key issue for me.

Cc @zeynep @SaskiaPopescu @j_g_allen @jljcolorado
3/ I have yet to see any major public health comms campaigns talk about when 6 feet apart is *not* enough, the need for better ventilation, or the need for better masks in certain high-risk situations.

And many of the official entities won’t do it unless CDC says so first.
Read 5 tweets

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