An update from Dr. Trevor Bedford, U.W. infectious disease specialist, on WA's COVID-19 cases.

[pnwmom]

He wrote a few days ago about the research showing that it's likely coronavirus has been spreading silently in WA state for more than 6 weeks now. Today's series of tweets were a follow up. His group has traced the links between two separate cases over a period of time. Between these two cases ALONE, there may be hundreds of other linked cases.

But there could also be other cases not related to this chain that haven't been discovered yet.

https://threadreaderapp.com/thread/1234588787641970689.html

1/11
As before, the genomic data support a linkage between the case WA1 from Jan 19 and the case WA2 from Feb 24, both from Snohomish County. 2/11

This suggests that the case WA1 infected someone who was missed by surveillance due to mild symptoms and a transmission chain was initiated at this point in mid-Jan. 3/11

Because the case definition from mid-Jan until Feb 27 required direct travel from China, any of these subsequent cases in the transmission chain would not have been tested for #SARSCoV2. 4/11

Assuming an introduction into Snohomish County on Jan 15, Mike Famulare @IDMOD_ORG simulated onward transmission using consensus epidemiological parameters curated by the @MIDAS_Network 5/11

Running these simulations forward with a mean doubling time of 6.1 days, we estimate the number of current infections in this transmission chain on March 1 to be 570 with an 90% uncertainty interval of between 80 and 1500. 6/11

In addition to this "bottom-up" approach, Mike used a "top-down" approach in which we accounted for the single positive screening result out of the number of samples screened to date along with census information. 7/11

This approach leads to a similar estimate of the number of current infections at 330 with a 90% uncertainty interval of between 20 and 1500 infections. 8/11
We believe this particular transmission chain will have a foci in Snohomish County. We're working as fast as possible to understand extent of spread in the greater Seattle area. 9/11

Please consider this to be a preliminary analysis. We are actively working on this and will continue to update our numbers. 10/11

We are hugely thankful to @SnoHD, @KCPubHealth and @WADeptHealth for their support and clear thinking for state and local public health. They are doing a fantastic job. 11/11

[KY_EnviroGuy]

1. Another key link for disease status in Washington state.....

Dr. Jeffrey Duchin
Health Officer & Chief, Communicable Disease EPI/Immunization Section, Public Health - Seattle & King County
Professor in Medicine/Infectious Diseases, U Wash
Seattle, WA

Twitter link: https://twitter.com/DocJeffD

Recently posted:

Link to tweet

Thanks for your update, Pwnmom.......

Wishing the best for our brothers and sisters in WA..........

[pnwmom]

2. Thanks for this link, too, KY!

At least the scientific community is working hard on this -- everything depends on them now.