A COVID-19 outbreak among 81 workers at Viracon’s architectural glass factory caused the Owatonna plant to close down for deep-cleaning for two days last week, health officials said.

The plant has the fourth largest outbreak among manufacturers in Minnesota, behind meat-processing facilities JBS in Worthington, Jennie-O Turkey Store in Willmar and Melrose, and Pilgrim’s Pride in Cold Spring, the Minnesota Department of Health (MDH) said.

The company said it has been following Centers for Disease Control and Prevention protocols since it had its first case.

Viracon spokesman Jeffrey Matthews said more than the 81 workers were sent home on paid leave after detailed contact tracing revealed possible exposure. Some of the quarantined workers have begun to return to work, he said.

The 2 million-square-foot factory has 1,500 employees covering multiple shifts, Matthews said, adding that workers are naturally spread out.

Since learning of sick workers, the company also is taking the temperatures of all factory workers before they enter the Owatonna plant, said Jeff Huebschen, vice president of investor relations for parent company Apogee Enterprises, in an e-mail.

“In recent weeks there has been an increase in positive COVID-19 cases in the communities surrounding our Viracon factory in Owatonna, and in our workforce which comes from those communities,” Huebschen said. “We have contact-traced all employees with symptoms and based on employee interviews, we do not believe the virus is being transmitted at Viracon.”

Amy Caron, the public health director for Steele and Dodge counties, said Steele County knows of an outbreak at an apartment complex in Owatonna and that state officials are bringing meals and medicine to the sick.

A few weeks ago, Daikin Applied America in Owatonna also had at least one worker sickened by the virus.

As of Tuesday morning, Steele County had 115 residents who had tested positive for COVID-19, according to the MDH.

To the north, Rice County — where the city of Faribault is located — had 270 cases.

Just east of Steele County, Dodge and Olmsted counties had a respective 39 and 479 cases. The city of Rochester is in Olmsted County.

Huebschen said that when it learned of COVID-19 cases in Owatonna, Viracon started doing health interviews, temperature screening, increased workplace disinfecting, and mandatory quarantines for anyone in close contact with infected individuals.

Quarantined employees receive an additional 80 hours of paid time off.

Any employee who is uncomfortable coming to work is given an unpaid leave of absence with paid medical benefits, he said.

Viracon is well known for making the exterior glass that covers U.S. Bank Stadium in Minneapolis and other famous buildings such as the World Trade Center in New York and the Taipei 101 skyscraper in Taiwan.

To date, the biggest outbreaks in Minnesota have been at the JBS pork-processing plant in Worthington, with more than 600 cases; the Jennie-O plants in Melrose and Willmar with more than 280 cases; and the Pilgrim’s Pride chicken plant in Cold Spring with over 190, the MDH said.

Many of the nation’s largest outbreaks have been in meatpacking plants, although North Dakota had a large surge of cases at the LM Wind Power turbine plant in Grand Forks.

Since the outbreaks, many Minnesota factory owners have embraced personal protective equipment, social distancing requirements and temperature checks at entrances.