Louise Smith, director of public health at Norfolk County Council, said officials were "monitoring the situation" at Banham Poultry near Norwich to prevent further transmission.
"We are working with colleagues at Public Health England, the NHS and Breckland Council following an outbreak of coronavirus at [the site] in Attleborough," she said.
“The management team at Banham Poultry has acted quickly to help prevent the spread of the virus and is working closely with us to trace the contacts of those who have tested positive."
Blaine van Rensburg, managing director of Banham Poultry, said the factory, which employs several hundred workers on a 12-acre site, will remain open while management work to prevent further spread.
“The safety of our staff, customers, and the wider public is really important to us and we are working with public health authorities to make sure we are doing absolutely everything we can and following all of the correct procedures.
“We have already invested in a range of procedures and protective equipment to keep our staff as safe as possible.”
Norfolk County Council are using test and trace to track down anyone who may have been in contact with infected workers.
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