Most of the coronavirus cases in the New York City area arrived via flights from Europe, say genome researchers. And it appears that COVID-19 was in circulation in the region in mid-February, about two weeks before the first confirmed case was in the books, report the New York Times and CNN. Researchers figured this out by studying minor mutations in the coronavirus genome in patients and tracing it back. "The majority is clearly European," says Harm van Bakel, a geneticist at Icahn School of Medicine at Mount Sinai and co-author of one new study. Specifically, about two-thirds of the cases are from the UK and countries including Austria, France, and the Netherlands, says another researcher, Adriana Heguy of New York University, per Bloomberg News.
The NYU group and the Mount Sinai group separately reached similar conclusions about the European origins. The US put travel restrictions into place early on travel from China, where the outbreak was first detected in late 2019. But no such restrictions were in place for flights from elsewhere. As a result, "SARS-CoV-2 came to New York City and environs predominately via untracked transmission between the United States and Europe, with only limited introduction from China," says the Mount Sinai team. Heguy says early, aggressive testing in the US could have helped ward off trouble. "It was a disaster that we didn’t do testing," she says. Researchers found that some cases in the New York area did originate directly from Asia, as well as from the West Coast, but most were from Europe. (Read more coronavirus stories.)