There were multiple introductions of SARS-CoV-2 into the Washington, DC, area during the late winter, the Washington Post reports.
Researchers analyzed 620 viral samples collected between March 11 and March 30, 2020 by the Johns Hopkins Health System and generated 114 complete viral genomes. As they report in a preprint posted to MedRxiv, Johns Hopkins University School of Medicine's Heba Mostafa and her colleagues found that these sequenced viral samples belonged to all five of the major viral clades that have been identified by NextStrain. This finding, they add, suggests multiple viral introductions into the region and underscores its connectivity, both domestically and internationally.
"There were probably five or more introductions sometime before the end of March," co-author Shirlee Wohl from Johns Hopkins Bloomberg School of Public Health tells the Post. "Even as early as March, the first three weeks of the outbreak, we were already seeing diversity rivaling the global diversity of this virus."
The Post notes that the study, which has not yet undergone peer review, did not determine where those introductions originated from.