An update about what we're able to infer about the Washington State #COVID19 outbreak from screening and viral sequencing by @UWVirology and @seattleflustudy. 1/12
Five new genomes were shared yesterday by @UWVirology via @GISAID bringing the total sequenced from the state to 18, of which all 17 community cases continue group into a single outbreak clade. 2/12 
This genetic structure argues for a single introduction event driving the cases that we're now seeing and thus we still feel that the forward-simulation approach described here is an appropriate method to estimate current number of infections. 3/12
This approach by @famulare_mike estimates 1100 active infections on March 10 (90% uncertainty interval between 210 and 2800 infections). 4/12
In addition, we can look more directly at surveillance data to see trends in positive specimens. This approach benefits from a wide swath of specimen collection conducted by the team at the @seattleflustudy. 5/12
Here, in another analysis by @famulare_mike, we show positive research tests through time, how many tests we ran and the proportion of positive tests. All dates are based on when samples were collected. 6/12
The main result here is that roughly 1% of people presenting with acute respiratory infections were testing positive for #COVID19 between Feb 20 and Mar 3. The red box is calling out lack of data for the most recent few days. 7/12
This points to a growing outbreak of #COVID19 in the greater Seattle area. If steps are not taken to increase social distancing as recommended by @KCPubHealth and @WADeptHealth, I fully expect cases to keep climbing. 8/12
There are individual actions you can take to help even if you do not have the luxury of being able to work from home. 9/12
We will be watching for increases in positivity over time as a signal for increasing community spread as well as analyzing prevalence across geography and across age groups and hope to report on this soon. 10/12
A side note, I believe that the reason @UWVirology is seeing 7%-13% rates of positivity () is because they are testing specifically for #COVID19 vs the @seattleflustudy research samples have been general acute respiratory disease. 11/12
Huge thanks to @HelenChuMD, @lea_starita, @mjonasrieder, @debnick60, @JShendure, @trs, @databae_, @KiraNewmanMDPhD, @pavitrarc, @GreningerLab, @IDMOD_ORG, @BrotmanBaty, @KCPubHealth, @WADeptHealth, @SnoHD, @CDC_AMD 12/12
