(This analysis and tweet thread in collaboration with @famulare_mike) The existence of a community transmission cluster of #COVID19 in Snohomish and King Counties is now supported by 8 confirmed and sequenced cases (). 1/7
As of today, in addition to the one traveller case, there are ~60 more cases in King and Snohomish counties from which we don't yet know the sequences. 2/7
Many of them are surely related to this cluster and some may be recent traveller importations. But some may also represent other clusters not yet confirmed. The model below describes our best estimates for only the confirmed cluster. 3/7
Using forward simulation, with a doubling time of 6.2 (5.1, 8.2) days, we estimate the prevalence of active infections on Mar 5 is 620 (90% uncertainty interval 120, 1600). 4/7
If growth continues unabated, this cluster alone may be responsible for 1100 (210, 2800) active infections by March 10 and 2000 (370, 5000) by March 15. 5/7 
We think this phylogenetic evidence continues to support the comprehensive actions recommended by @KCPubHealth, @SnoHD, @WADeptHealth to reduce the rate of transmission. kingcounty.gov/depts/health/c… 6/7
We thank @seattleflustudy, @HelenChuMD, @lea_starita, @mjonasrieder, @debnick60, @JShendure, @trs, @databae_, @UWVirology, @pavitrarc, @GreningerLab, @IDMOD_ORG, @BrotmanBaty, @KCPubHealth, @WADeptHealth, @SnoHD, @CDC_AMD 7/7
