The two companies will pay penalties under agreements with the Environmental Protection Agency, which accused both of violating rules around the use of a refrigerant at their plants.
Of the 403 employees and contractors tested at the Portland poultry plant, 51 tested positive, the company said. The plant was closed for deep cleaning and sanitization, and production resumed last week.
The Portland chicken processing plant, formerly Barber Foods, has more than 400 employees and is the first business in the state that isn't a care facility to report an outbreak of the novel coronavirus.
Barber Foods in Portland has expanded a recent product recall to 1.7 million pounds of frozen chicken products that may be contaminated with salmonella.