California reported its second case of community transmission of the coronavirus in two days,a 65-year-old woman in Santa Clara County who has no known history of travel to countries hit hard by the outbreak, people familiar with the situation said Friday.
That means the virus appears to be spreading among at least two separate communities, about 90 miles apart, according to people who spoke on condition of anonymity because they were not authorised to discuss the details. On Wednesday, health authorities revealed the nation's first case of community transmission, a woman in Solano County, California.
There is no apparent connection between the new patient and anyone else with the disease, known as covid-19.
"I think there's a strong possibility that there's local transmission going in California," said Jennifer Nuzzo, senior scholar at the Johns Hopkins Center for Health Security. "In other words, the virus is spreading within California, and I think there's a possibility other states are in the same boat - they just haven't recognised that yet."
Two students in Palo Alto, a city of 67,000 in the northwestern corner Santa Clara county, also may have been exposed to the virus, according to a letter to parents from the school's superintendent Friday.
The children are from the same family. One is in high school and the other is in middle school.
The school system said that "as a precautionary measure, the district immediately took action and the two students were sent home and will be excluded from attending school until we receive more information."
In a news release, the county described the newly-diagnosed Santa Clara county patient as "an older adult woman with chronic health conditions who was hospitalised for a respiratory illness."
The virus is known to cause more severe illness in older people and those with underlying illnesses such as cardiovascular disease and diabetes. But the symptoms are milder in more than 80 percent of current patients.
Little else is known about the woman's case, including her condition or how long she was in the community while infectious.
To date, the virus, which originated in Wuhan, China, has sickened more than 84,000 people and killed more than 2,800. It has moved into 56 countries, breaking out in places such as South Korea, Iran and Italy. With one case confirmed in New Zealand
Now it appears to be reaching into the heart of Silicon Valley, home to some of the world's largest technology companies - including Google, Apple and Tesla - and the city of San Jose, whose population exceeds 1 million. Santa Clara county is home to 2 million residents.
In their news release, Santa Clara health officials warned residents that "now is the time to prepare for the possibility of widespread community transmission." The county will be conducting surveillance to determine how widely the disease has spread, she said.
"This new case indicates that there is evidence of community transmission, but the extent is still not clear," said Sara Cody, the county's health officer. "I understand this may be concerning to hear, but this is what we have been preparing for. Now we need to start taking additional actions to slow down the spread of the disease."
On Tuesday, the Centers for Disease Control and Prevention gave much the same guidance to the rest of the country, warning Americans to prepare for the inevitable spread of the virus in their communities. If transmission becomes more widespread, and severe illnesses occur, that could mean school closings, companies mandating telework and limits on or postponements of mass gatherings, said Nancy Messonnier, a top CDC official.
The CDC has been under intense pressure to step up testing for the virus. The agency promised Friday that it would be providing more test kits to states in coming days to allow for more rapid identification of infected people.
The discovery of a second case "supports what we are trying to do with basic infection and case identification," said Saskia Popescu, senior infection prevention epidemiologist for Honor Health, a hospital system in Phoenix. "We need to focus on pragmatic and scientifically-based measures and not hit the panic button. We know how to protect ourselves."