Eight employees of the Tyson Foods poultry processing plant in Portland have tested positive for COVID-19, prompting state officials to recommend testing of all 400 employees and company officials to consider idling production.

It is believed to be the first workplace outbreak in Maine outside of a health care facility.

State health officials said Tyson is “making significant strides” to implement all of their public health recommendations. At 8 a.m. Wednesday, the state recommended universal screening of all plant employees. By 1 p.m., five hours later, Tyson had agreed, and was willing to consider idling production while that testing takes place, they said.

“As it turns out, they were already heading in the same direction,” Dr. Nirav Shah, director of the Maine Center for Disease Control and Prevention, said at his Wednesday COVID-19 briefing. “Many of the recommendations we offered were things they had already contemplated doing.”

The Maine CDC first learned a plant employee had tested positive for COVID-19 on April 16, CDC spokesman Robert Long said. The agency contacted management as part of its standard follow-up with all close contacts of people who test positive for the novel coronavirus, he said.

Late Tuesday afternoon, 10 days later, the state learned that conditions at the Tyson plant had turned into an outbreak, which is defined as three or more confirmed cases that are “epidemiologically linked” at the same facility, Long said. It was not clear when Tyson learned it had multiple infected employees or when the eight infected employees stopped working, but they were not working Wednesday.

As a result of the outbreak, Long said, Maine has asked Tyson to immediately test all workers there, require those who test positive or refuse to take the test to stay away from work, idle the plant until test results come back, and clean the plant according to public health guidelines.

A Tyson spokesman said the company will work with the state CDC and an outside contractor to test all its Portland employees “in the coming days.” The company didn’t respond to Shah’s statement that it was willing to idle its production of frozen stuffed chicken breasts.

“Our workplace safety efforts are significant and strictly enforced at all locations,” Tyson spokesman Worth Sparkman said. “We’re implementing social distancing in our plants based on CDC and industry guidance, such as increasing the distance between workers on the production floor, installing workstation dividers and barriers in our break rooms.”

Workers sort frozen chicken products in the plant in Portland in 2011, when the company was Barber Foods. The current owner, Tyson Foods, says it is willing to consider idling the plant while its 400 employees are tested for coronavirus. Meat processing workers are believed to be highly susceptible to the virus because they stand close together on production lines and congregate in locker rooms and cafeterias. Carl D. Walsh/Staff Photographer

Sparkman said he could not say what specific measures the Portland facility had already taken or planned to take as a result of the outbreak. Nationally, he said, Tyson is screening workers for fevers as they arrive at work, requiring employees to wear face coverings at work and stepped up daily deep cleanings.

Other communities with outbreaks at meat processing plants have complained that management put the public at risk by failing to inform workers of positive tests, and refusing to close when the cases surged, but Shah described his experience with Tyson as a collaborative one.

“It hasn’t really come down a ‘thou shall,’ ” he said. “It really has been a ‘we recommend’ and they concur.”

Sparkman did not respond to follow-up questions later Wednesday.

More than a half dozen U.S. meat processing plants have shut down because of COVID-19 outbreaks over the past month. Meat processing employees are believed to be highly susceptible due to plant conditions, standing shoulder-to-shoulder on the line and congregating in crowded locker rooms and cafeterias.

Because the workers are vulnerable, so too is the supply of that meat, health officials say.

Tyson last week shut down a major plant that is critical to the nation’s food supply after it was blamed for causing a COVID-19 outbreak in Waterloo, Iowa. But President Trump issued an executive order Tuesday requiring meat processing plants to remain open “to ensure a continued supply of protein for Americans.”

Tyson Foods Chairman John Tyson has taken out full-page ads in national newspapers urging federal, state and local health officials to work with the nation’s meat processing plants to find a way to stay open despite the new health challenges posed by COVID-19.

In the ads and on the company’s webpage, Tyson sounded the alarm: “the food supply chain is breaking.”

“We’re being forced to shutter our doors,” Tyson warned. “This means one thing – the food supply chain is vulnerable. … We have a responsibility to feed our country. It is as essential as healthcare. This is a challenge that should not be ignored. Our plants must remain operational so that we can supply food to our families.”

Tyson Foods bought the 150,000-square-foot plant on St. John Street that had once been Barber Foods in 2017 as part of a $4.2 billion acquisition of AdvancePierre of Ohio. When AdvancePierre bought Barber in 2011, about half the employees lost their jobs, but it remained one of Portland’s biggest employers.