New coronavirus case escalates US response

Public health officials were retracing the steps of a Northern California woman on Thursday believed to be the first person in the U.S. to contract the highly contagious coronavirus without traveling internationally or being in close contact with anyone who had it.

The diagnosis, confirmed Wednesday, marks an escalation of the worldwide outbreak in the U.S. because it means the virus could now spread beyond the reach of quarantines and other preventative measures.

But state health officials were quick to reassure the public on Thursday that such a scenario was inevitable and the risk of widespread transmission remained low.

Solano County Public Health Officer Dr. Bela Matyas said public health officials have identified dozens of people - but less than 100 - who had close contact with the woman.

Those people are quarantined in their homes.A few have shown symptoms and are in isolation, Matyas said.The case raised questions about how quickly public health officials are moving to diagnose and treat new cases.

State and federal health officials disagreed about when doctors first requested the woman be tested.