All 800 workers at Banham Poultry will now be tested for coronavirus, health chiefs said on Friday.
It has been a week since the first worker at the meat factory near Attleborough tested positive for Covid-19, sparking an outbreak amongst 80 staff.
In response, the factory closed its cutting area and tested 376 workers.
But Norfolk’s director of public health, Dr Louise Smith, said on Friday that all 800 staff who had worked on the site since August 1 would now be tested.
She said that testing had already begun and would continue until next week.
Bernard Matthews also confirmed on Friday that a worker at its poultry factory at Great Witchingham had tested positive for Covid-19.
But no other staff returned a positive test in 26 results.
Dr Smith said there was no evidence of a wider outbreak at Bernard Matthews, but added that the region’s poultry producers would be meeting next week to discuss what more the industry can do.
She ruled out regular testing of all poultry workers.
On Thursday, Banham Poultry defended its coronavirus prevention measures, stating it had teams in place to monitor social distancing and provided staff with appropriate PPE.
That followed criticism from one visitor about a lack of face masks and social distancing.Leader of the council Andrew Proctor said the council was supporting the company and staff who have to self-isolate.
He said the council backed calls from Mid Norfolk MP George Freeman for government support.
Mr Freeman has argued that the government should provide compensation to help companies like Banham Poultry “take tough steps to protect the rest of us”.
Dr Smith said there was not a wider risk to the public from the outbreak and the factory remains open.
The extra cases have led to a sudden surge in the coronavirus rate in Great Yarmouth, where many of the workers live, and Breckland, where the factory is based.
The infection rate in Great Yarmouth has increased to 24 per 100,000 and in Breckland to 17 per 100,000, as of Friday.
That is up from five in Breckland at the same time last week and three in Great Yarmouth.
The infection rate in Norwich has also risen from three people per 100,000 last week to eight by Friday.
In all other areas of the county it remains steady and there is no risk of a local lockdown.
•Anyone who needs help self-isolating can contact the Norfolk Assistance Scheme on 01603 223392.
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