Thanks to @seattleflustudy and @UWVirology, we have new genomic data on the spread of #COVID19 in Washington State with 2 new #SARSCoV2 genomes sequenced today, bringing the total number of WA genomes to five. 1/8
Four of these five genomes are all part of a single cluster that appears to descend from the initial WA1 case identified in mid-Jan, including the case in Snohomish as well as two cases from King County. 2/8 nextstrain.org/ncov?branchLab… 
This directly suggests that the transmission chain initiated in mid-Jan by case WA1 in Snohomish is responsible for at least a portion of the cases appearing in Seattle. 3/8
Given these are part of a single transmission chain, our forward simulations should still capture the predicted extent of spread with a median estimate of 570 current infections with a 90% uncertainty interval of between 80 and 1500. 4/8
Fortunately, we were able to get confirmation that case WA3-UW1 was actually a direct travel import. I did not know this yesterday when I made this statement: 5/8
This is good news! (In a terrible situation) We only know of the one transmission chain and we think this contains ~600 (but perhaps up to 1500) infections today. Our numbers among cases with known genetic origins are not up from where they were on Monday. 6/8
That said, ~600 active infections is still a very large number. @KCPubHealth and @WADeptHealth have been tireless in their efforts here and I applaud steps being taken to encourage social distancing: publichealthinsider.com/2020/03/04/sta… 7/8
Huge props to everyone who was involved in generating this absolutely critical data. @UWVirology: @pavitrarc @GreningerLab, @seattleflustudy: @HelenChuMD @lea_starita @BrotmanBaty @JShendure @famulare_mike Jan Englund Mark Rieder (and others I'm missing here) 8/8
@UWVirology @pavitrarc @GreningerLab @seattleflustudy @HelenChuMD @lea_starita @BrotmanBaty @JShendure @famulare_mike Also Northwest Genome Center @debnick60 @trs
