Danish Crown said 120 employees tested positive for the virus in an initial round of tests of 600 employees present.
After retesting, 22 additional infections were detected.
“For this reason, we are closing the abattoir for at least a week to try to break the chain of transmission among employees on site,” Danish Crown said in a statement.
The company, one of Denmark’s biggest exporters, is the largest pork-product maker in Europe. Numerous slaughterhouses have been hit with the virus in recent months, especially in neighboring Germany.
The cluster at Ringsted is the main active one in Denmark. Cases in the Scandinavian nation have risen sharply in recent days, with the government shelving a plan to ease restrictions at concert halls and nightclubs.
Aarhus, the country’s second-biggest city, has registered several dozen infections.