PORTLAND, Maine (WGAN) More than half of the workers who tested positive for the coronavirus at a food-processing plant in Portland showed no symptoms, Tyson Foods said.

Fifty-one workers and contractors who work in the plant tested positive but 31 individuals were asymptomatic and otherwise would not have been identified, the company said.

Testing took place between May 2 and 4 while the plant was temporarily closed for cleaning and sanitation. The plant resumed limited production on May 7.

Tyson has increased short-term disability coverage to 90% of normal pay until June 30 to encourage team members to stay home when they are sick. All told, about 403 people work in the plant.