BP’s operations center at Prudhoe Bay. (Elizabeth Harball/Alaska’s Energy Desk)

Oil and gas company BP confirmed Tuesday that one of its workers at Prudhoe Bay has tested positive for COVID-19. It’s the first confirmed case of the illness at the massive oil field in northern Alaska, where many workers live in close quarters.

BP is the operator of the field. In a statement Tuesday, the company said it’s “following procedures and protocols to minimize the risk of COVID19 and ensure the safety of our people.” It also said it was “eliminating all non-essential activity on the Slope.”

Catch up on the latest news on coronavirus in Alaska.

BP spokeswoman Megan Baldino declined to answer questions on Tuesday about the condition of the employee, when they were tested and how many others they have exposed.

During a news conference Tuesday, Dr. Anne Zink, Alaska’s chief medical officer, said the worker was from out of state. However, in a statement later that night, Alaska Department of Health and Social Services Commissioner Adam Crum said that was incorrect.

The employee is an Alaska resident who had previously traveled out of state, the statement said.

“The patient traveled to the North Slope on March 25, and displayed symptoms within two days of arriving,” said Crum’s statement. “He was tested and put in quarantine, as were his immediately identified close contacts.”

While some companies, including BP, are having their workers go through health screenings before they fly to Deadhorse, Zink said that doesn’t always catch COVID-19. She said, “one of the tricky things about the disease is that people can be completely asymptomatic or mildly symptomatic.”

“And despite screening and even potentially testing, it doesn’t necessarily prevent someone from feeling fine and then going someplace and starting to develop symptoms,” Zink said, underscoring the importance of social distancing.

She said the Prudhoe Bay worker “got screened and then got up to the Slope and then started to feel ill.”

Zink said BP had a plan to test and isolate the worker, and quarantine others. She said the state continues to work with the company.

Baldino declined to say how many workers were quarantined on the Slope.

The worker diagnosed with COVID-19 had returned to Alaska before Gov. Mike Dunleavy enacted a mandatory two-week quarantine for people traveling into the state, according to Crum’s statement.

In an interview last week, Baldino said BP had deployed several measures to try to prevent the spread of the coronavirus at Prudhoe Bay. That includes extending many workers’ shifts to at least three weeks, instead of two, and increasing cleanings.

Related: Wristbands, longer shifts, fever checks: How Alaska oil companies are responding to the global pandemic

Baldino said Saturday that the company would also have its out-of-state workers self-quarantine for two weeks in Alaska before flying to the Slope.

In a statement Tuesday, BP said activity at Prudhoe Bay is now “limited to safety critical and regulatory compliant activity.” It’s ending this year’s development drilling.

As Alaska’s oil industry responds to the coronavirus pandemic, it’s also grappling with cratering oil prices.

Reach reporter Tegan Hanlon at thanlon@alaskapublic.org or 907-550-8447.