Officials scramble to retrace steps of California coronavirus case

Guardian staff and agency
Photograph: Justin Sullivan/Getty Images

California and federal officials were in the midst of an intense effort on Thursday to retrace the movements of a northern California woman believed to be the first person in the US to contract the highly contagious coronavirus with no known connection to travel abroad or other known causes.

The diagnosis, confirmed on Wednesday, marks an escalation of the worldwide outbreak in the US because it means the virus could now spread beyond the reach of quarantines and other preventive 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.

The new California case raised questions, however, 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.

Related: New coronavirus case in northern California may be first with no link to travel

Doctors at the UC Davis Medical Center said they asked the US Centers for Disease Control and Prevention to test the woman for the virus on 19 February. But they said the CDC did not approve the testing until Sunday “since the patient did not fit the existing CDC criteria” for the virus, according to a memo posted to the hospital’s website.

Richard Quartarone, a CDC spokesman, said a preliminary review of agency records indicates the agency did not know about the woman until Sunday, the same day the woman was first tested.

Quartarone said the agency was concerned about reports of delayed testing and was “investigating this carefully”.

The woman lives in Solano county, home to Travis air force base, where dozens of people infected in China or on cruise ships have been treated. But Sonia Angell, director of the California department of public health, said there was no evidence the woman had any connection to the base.

The California governor, Gavin Newsom, said the state was limited in how many people it could test because it only had 200 testing kits. But he said federal officials have promised to send many more in the coming days.

“I’m not going to politicize this moment, and I’m not going to point fingers,” Newsom said. “We have had a very strong working relationship with the [Trump] administration.”

Investigators were focused on tracing the woman’s steps to figure out how she got the virus and who else she may have unwittingly infected.

The woman, who has not been identified, first sought medical care at NorthBay VacaValley hospital, in Vacaville, a city of more than 100,000 people about 55 miles (88 kilometers) north-east of San Francisco.

She stayed there for three days and was then transferred to a Sacramento hospital where she later tested positive for the virus.

Ten experts from the CDC arrived on Thursday and were heading to Vacaville to help with the search, said Dr James Watt, interim state epidemiologist at the California department of public health.

With the patient as ground zero, they are interviewing immediate family members. Then, as with any similar case, they are expanding the net to include more distant family members who may have been in contact, social gatherings the patient may have attended, and any possible time spent at work or events.

They are not too worried, for now, about casual contact, because federal officials think the coronavirus is spread only through “close contact, being within six feet of somebody for what they’re calling a prolonged period of time”, said Watt, who was the state’s deputy epidemiologist for 10 years before he took the interim post two months ago.

“That’s more than casual contact at a grocery store,” Watt said. “That’s where our focus is going to be. What was the pattern of disease transmission?”

Dr Bela Matyas, the Solano county public health officer, 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.

Following the emergence of the California case, the CDC updated its testing criteria on its website, a move that had been in the works for days, according to a federal official familiar with the change.

Previously, the number of people being tested in the US had been limited to those who, in addition to showing symptoms, had a history of travel to countries affected by the disease or contact with those who have done so, said Lauren Sauer, director of operations at Johns Hopkins University’s office of critical event preparedness and response.

“In the US, people are sticking pretty closely to that definition,” Sauer said. But the increasing cases on other continents “are demonstrating we need to do a better job than just where the outbreak originated”.

The CDC will continue to advise testing people who have traveled to certain outbreak areas and have fever and certain other symptoms. But now testing is also appropriate if such symptoms exist and flu and other respiratory illnesses have been ruled out and no source of exposure has been identified. As part of that, the CDC has expanded the list of countries that are red flags for testing to include not only China but Iran, Italy, South Korea and Japan.

UC Davis medical center, which has treated other coronavirus patients, has been taking infection prevention precautions since the patient arrived. Officials believe there was a small chance that others at the facility were exposed to the virus and they were asked to stay home and monitor their temperatures, the memo said.

All of the 59 other cases in the US have been for people who had traveled abroad or had close contact with others who traveled. Health officials have been on high alert for so-called community spread.

Earlier US cases included 14 in people who returned from outbreak areas in China, or their spouses; three people who were evacuated from the central China city of Wuhan; and 42 American passengers on the Diamond Princess cruise ship who were evacuated by the federal government to the US after the ship docked in Japan.

The global count of those sickened by the virus hovered around 82,000 on Thursday, with 433 new cases reported in China and an additional 505 in South Korea.

The new virus is a member of the coronavirus family that can cause colds or more serious illnesses such as Sars and Mers.

The virus can cause fever, coughing, wheezing and pneumonia. Health officials think it spreads mainly from droplets when an infected person coughs or sneezes, similar to how the flu spreads.

Officials are advising people to take steps to avoid infection with coronavirus or other respiratory infections like colds or the flu, including washing hands with soap and water and avoiding close contact with people who are sick.