Alliance for Pandemic Preparedness

May 5, 2021

Viral Genomes Reveal Patterns of the SARS-CoV-2 Outbreak in Washington State

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  • The rapid spread of the D614G variant in Washington State was a result of multiple introductions into areas with different levels of ongoing lockdown, according to a phylogenetic analysis of 3940 SARS-CoV-2 sequences from Washington State and county-level mobility data collected between February and July 2020. Sequences derived from out-of-state introductions were unevenly distributed, with D614G cases comprising a higher proportion of introductions. By the time statewide measures were implemented, decreased mobility (as assessed by Google workplace mobility data) in King County had coincided with decreased reproduction numbers for both D614G and 614D variants, while cases of D614G were more widespread in regions of the state where mobility was increased.  Patients infected with D14G had significantly lower cycle threshold values (corresponding to higher viral load) on initial testing. A review of evidence from 248 clinical records did not suggest that D614G impacted disease severity or patient outcomes.

Müller et al. (May 3, 2021). Viral Genomes Reveal Patterns of the SARS-CoV-2 Outbreak in Washington State. Science Translational Medicine. https://doi.org/10.1126/scitranslmed.abf0202