2 Sisters chicken factory in Llangefni and Rowan Foods in Wrexham recorded nearly 100 workers between them having tested positive for the virus.
Public Health Wales confirmed 58 cases at 2 Sisters chicken factory and another 38 at Rowan foods.
Health Minister Vaughn Gething said the factory outbreak was a “concern” and insisted that the Welsh Government was managing the incident.
2 Sisters have since stopped production and closed the Anglesey site.
The chicken factory has supplied local authorities, hospitals, restaurants and small businesses amidst the pandemic.
2 Sisters have assisted supermarkets such as Marks and Spencer, Aldi, Asda, Co-op, Morrisons, Sainsbury’s, Tesco and Waitrose, as well as supplying to fast food franchise KFC.
Staff at the factory are set to be tested, with all workers being contacted by the company to take part in tests.
Llangefni joins Bangor in creating a testing site, with plans to set up another operation in Holyhead.
Rowan Foods issued a statement on the incident explaining the company had introduced measures to prevent the spread of the virus.
Rowan Foods said: “As you would expect we have made significant operational changes at the site to maintain social distancing wherever practically possible, including various mitigations such as screens and visors where this is not always possible.”
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“The safety of our colleagues remains our priority and our focus is remaining COVID-19 secure as a site.
“We must do all we can to take individual responsibility and follow government guidelines at all times for our own safety and the safety of our colleagues.
“Whilst we are seeing a number of cases on site, Public Health Wales support our view that there is no clear evidence to suggest that there is a spread of the virus within the site, we are seeing a reflection on site of the increases in cases within the locality,
“We will continue to do all we can to remain vigilant and to keep our colleagues and families safe.” Oscar Mayer said.
Health Minister Gething explained that this incident should remind the public to follow government guidelines.
He said: Its rhetoric’s the importance of our test, trace, protect system, and people do need to really follow the advice they are given on getting a test and on self-isolating.
“Given that this is a closed setting in which these people would have been working, I’m obviously concerned we may well see more confirmed cases of coronavirus.
“So if there is a proper outbreak that is being managed, if you like the normal way, we would minus significant outbreaks here in Wales, there’s partnership between Public Health Wales, the local health board and indeed Anglesey council working together with the employer.
“I would ask people to recognise this reiterates the seriousness of coronavirus, the need to follow the guidance, get a test and follow the advice from test, trace, protect to self-isolate to protect you, your family and other people around.”