Almost 300 workers at the Greencore sandwich site in Northampton have tested positive for Covid-19.
The food-to-go business is working with local health authorities after the discovery of the outbreak, which follows a rise in cases in the Northampton area.
So far 292 workers are known to be infected, with 79 identified through NHS testing.
Greencore this week brought in a private testing firm when it became clear there was an outbreak in the area, and this identified a further 213 cases.
Staff who have tested positive are self-isolating, while the site is continuing to operate.
Greencore said it is liaising closely with PHE East Midlands, Northamptonshire County Council and Northampton Borough Council, adding the authorities were “fully supportive” of the controls the business has on site.
“In each case we have immediately conducted contact tracing and instructed potentially affected colleagues to self-isolate,” said a spokesperson.
“All of Greencore’s sites have wide-ranging social-distancing measures, stringent hygiene procedures and regular temperature checking in place, and we are doing everything that we can to keep our people safe.”
Lucy Wightman, director of public health at Northamptonshire County Council, said Public Health England Midlands has been providing support to Greencore in managing the outbreak.
“It is evident that Greencore has highly effective measures in place and they continue to work extremely hard to exceed the requirements needed to be Covid-19 secure within the workplace,” she added.
Wightman explained that, as a result of the increase in cases in the area, businesses and workplaces were working alongside Northampton Borough Council and Public Health Northamptonshire to help employees understand the risks associated with car sharing, house sharing and sharing crowded areas during breaks or commuting to and from work.
“The guidance in the workplace is just as important as outside of work,” she added. “If individuals do not take responsibility for following the guidance that we have issued, then further intervention and a possible local lockdown will follow.”