The novel coronavirus began spreading in New York City in February, before widespread testing began, and the strain so far identified in local samples came from Europe, a scientist said.

Adriana Heguy, a geneticist at NYU Grossman School of Medicine who led the research, told AFP that tracing back the virus's chain of transmission will help policymakers make better informed social interventions in the future.

“It's very interesting that so far, the majority seem to be coming from Europe, and this is in part I think because there was a focus on stopping travel from China,” she said.