PandemicsAmid Spotty Response, COVID Silently Stalked U.S. for Weeks
Two new studies involving evolutionary genomics, computer simulations, and travel records from the COVID-19 pandemic suggest that inadequate travel monitoring, contact tracing, and community surveillance allowed the novel coronavirus to spread unchecked to and throughout North America and Europe in late January or early February.
Two new studies involving evolutionary genomics, computer simulations, and travel records from the COVID-19 pandemic suggest that inadequate travel monitoring, contact tracing, and community surveillance allowed the novel coronavirus to spread unchecked to and throughout North America and Europe in late January or early February.
The studies, published late last week in Science, traced the United States’ COVID-19 outbreak to a traveler who flew from China to Seattle in late January or early February, seeding the nation’s first outbreak, which then went undetected for 3 to 6 weeks.
Undetected, Unchecked
The first study, led by University of Washington researchers in Seattle, involved genomic analysis of 453 SARS-CoV-2 viruses, which cause COVID-19, collected from the Washington state outbreak from Feb 20 to Mar 15 and coronavirus testing of more than 10,000 respiratory specimens collected as part of the Seattle Flu Study from Jan 1 to Mar 15.
Finding that 84% of the virus genomes in Washington state were closely related and derived from a variant of the virus from Wuhan, China, the researchers concluded that the source of the outbreak probably was a traveler who flew from China to Seattle between Jan 22 and Feb 10.
The first confirmed US coronavirus case was identified on Jan 19 in a traveler, designated as “WA1,” who returned to Seattle on Jan 15 from Wuhan. The traveler’s virus genome was similar to others involved in the Washington state outbreak but different enough to make it unlikely that he or she was the source of the outbreak.
COVID-19 spread undetected in Washington state until Feb 28, after US Centers for Disease Control and Prevention testing criteria were broadened to include nontravelers, which the authors said highlights the importance of continuing widespread community surveillance even after an outbreak is controlled. “We see the combination of community surveillance, genomic analysis and public real-time sharing of results as empowering new systems for infectious disease surveillance,” they wrote.
Within a month, the state had reported 2,580 cases and 132 deaths, the result of both increased testing and community transmission.
The genomic sequences of most coronavirus samples collected from New York and Connecticut were different from those found in Washington state and similar to those from Europe, the researchers said. Virus samples from earlier in the pandemic and other locations will be needed to pinpoint the specific date and geographic origin of the introduction of the virus in Washington state, they said.
