Officials in Santa Clara County, Calif., announced late Tuesday that two residents there died of the coronavirus in early and mid-February, making them the earliest known victims of the pandemic in the United States.

The new information may shift the timeline of the virus’s spread through the country weeks earlier than previously believed…

“Each one of those deaths is probably the tip of an iceberg of unknown size,” Dr. Sara Cody, the county’s chief medical officer, said in an interview. “It feels quite significant.”

Dr. Cody said the individuals who died in February did not have any known travel histories that would have exposed them to the virus, which first appeared in China. They are presumed to have contracted the virus in the community, she said.