The company say they're awaiting guidance on its next steps.
Covid-19 tests on 210 staff members from Carroll's Cuisine in Tullamore have all come back negative.
The HSE took the swabs on Sunday as part of a serial testing programme.
Nine other members of staff, who were previously diagnosed with coronavirus, are still isolating.
The company says it's in contact with health officials for advice on the next steps to take - but the plant remains closed.