LOS ANGELES — The novel coronavirus spread on the west coast of the United States weeks earlier than initially believed, according to new information released by local public health officials this week.

Health authorities of Santa Clara County in the western US state of California confirmed Tuesday that two patients had died of COVID-19 at least three weeks before the first known US death from the novel coronavirus disease on Feb 29 in Kirkland in Washington State.

According to a statement issued by the Northern California county's Emergency Operations Center, the Medical Examiner-Coroner performed autopsies on two individuals who died at home in early February, and received results from the Centers for Disease Control and Prevention on Tuesday, which showed both tested positive for COVID-19.

"As the Medical Examiner-Coroner continues to carefully investigate deaths throughout the county, we anticipate additional deaths from COVID-19 will be identified," the statement said.

Patricia Dowd, a 57-year-old San Jose woman, who died at home on Feb 6.

Jeffrey V. Smith, Santa Clara county executive, told Xinhua in an email interview that "so far, this is the earliest death in the United States."

Santa Clara County's public health officer Dr. Sara Cody told media that Dowd and another 69-year-old man who died at home on Feb. 17 had no "significant travel history," and they presumably caught the virus through community spread.

Family members said Dowd, who worked as manager for a semiconductor company, became unusually sick in late January. She had flu-like symptoms for a few days, then appeared to recover. When she was found dead in early February, the initial culprit had appeared to be a heart attack, the Los Angeles Times reported this week.

"What these deaths tell us is that we had community transmission probably to a significant degree far earlier than we had known," Cody told reporters.

"When you have an outcome like death or ICU, that means that there's some iceberg of cases of unknown size that underlie those iceberg tips," she said.

Neeraj Sood, a professor at the Price School of Public Policy at the University of Southern California, told the Los Angeles Times that he believes the virus was circulating weeks before the newfound death.

"When you start seeing the first death, actually, the number of cases in the population is probably pretty high already. It's been in the community for a long time," Sood was quoted as saying by the Los Angeles Times.

"These patients apparently contracted the illness from community spread. This suggests that the virus was circulating in the Bay Area in January at least, probably earlier," Smith told Xinhua.

According to a new study released by researchers at Stanford University earlier this month, some 48,000 to 81,000 people in Santa Clara County alone may already have been infected with COVID-19 by early April, an indication that 2.5 percent to 4.2 percent of county residents may have antibodies.

There are 2,018 confirmed COVID-19 cases and 98 deaths in Santa Clara County so far, according to data released by the county's Public Health Department on Friday morning.