Almost 300 workers have tested positive for coronavirus following an outbreak at a factory in Northampton that makes M&S sandwiches. Greencore said some of its staff are self-isolating after a significant number tested positive for coronavirus. The company took the decision to proactively test workers as a result of a rise in cases in the town. A spokeswoman for Northamptonshire county council said 79 people returned positive NHS tests and a further 213 tested positive through Greencore’s private testing. In a statement, Greencore said: “As a result of the rising number of Covid-19 cases in the Northampton area, we took the decision to start proactively testing all of the colleagues at our Northampton site. We can confirm that a number of colleagues have tested positive for the virus and are now self-isolating. “We are liaising closely with PHE East Midlands, Northamptonshire county council and Northampton borough council, who are fully supportive of the controls that we have on site.” Greencore said in each case the company has conducted contact tracing and instructed potentially affected colleagues to self-isolate. The company added: “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. “As ever, the health and wellbeing of our colleagues is our number one priority.” Lucy Wightman, director of public health at Northamptonshire county council, said employees have been asked to “act now” after the number of confirmed cases in the town increased from 66 in the week ending 2 August to 85 for the week ending 9 August. The outbreak in a factory in Northampton follows a similar outbreak at an Asda-owned meat processing site in West Yorkshire, where 165 employees contracted the virus in June. The Guardian reported that more than 450 workers at four food factories across England and Wales had tested positive for coronavirus in June. Health officials had been closely monitoring clusters of new cases linked to food processing plants following similar outbreaks in France and the US. In the US, as many as 25,000 meat and poultry workers are reported to have contracted Covid-19, with at least 93 deaths. Northamptonshire county council said it has been working with colleagues at Greencore following the Covid-19 outbreak and that Public Health England Midlands has been providing support. Wightman added: “This has been supplemented by support from the local infection prevention and control team and Northampton borough council’s environmental health colleagues. 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. “Northampton borough has been experiencing a high number of cases over the last four weeks and residents and employees have been asked to ‘act now’ to follow additional measures, to avoid a local lockdown or further government intervention.” Ian Hodson, national president of the Bakers, Food and Allied Workers Union, said: “We have been concerned about Greencore. Since the outbreak in March our regional official has been in constant contact on numerous issues.”