More than 450 workers at four food factories across England and Wales have tested positive for coronavirus.
Kirklees council confirmed on Thursday that 165 employees of an Asda-owned meat processing site in West Yorkshire had contracted the disease after they had fallen ill earlier this month.
The Kober site, which employs more than 500 people, resumed production on Tuesday with “significant adjustments” to support physical distancing, the council’s director of public of health said.
It is the fourth food factory in England and Wales to have confirmed an outbreak of Covid-19 among workers, bringing the number of employees testing positive for the virus to 469.
Health officials are closely monitoring clusters of new cases linked to food processing plants amid concerns about potential outbreaks similar to those seen 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.
Public Health Wales confirmed on Wednesday that 200 coronavirus cases had been detected at a meat processing plant on Anglesey owned by 2 Sisters Food Group, the UK’s main suppliers of supermarket chicken.
Two other sites in Wales have also confirmed smaller outbreaks: 34 cases linked to Kepak in Merthyr Tydfil and 70 at Rowan Foods in Wrexham.
The confined working conditions and long periods spent by workers in close proximity – often 10 to 12 hours a shift – mean meat factories are at substantially heightened risk of spreading the coronavirus through human-to-human transmission, the US Centers for Disease Control and Prevention has said. The colder temperature in food factories is also thought to help incubate the disease for longer periods.
Rachel Spencer-Henshall, director of public health at Kirklees council, said: “I’d like to thank Kober for acting quickly and working with us and Public Health England to help manage this outbreak.
“They reopened their factory on 23 June on a reduced capacity and only colleagues that have been tested and declared fit to return are on site. We’re satisfied with health and safety measures on site which include separation of colleagues on different shifts and as an additional precaution, checking the temperature of colleagues before they enter the site.
“Our advice to residents is to continue to socially distance, wash hands regularly for 20 seconds with soap and water and get tested if they have symptoms. Providing you have not been contacted and told otherwise, you can continue to leave the house following the latest government advice.”
Unions have said the living conditions of many low-paid workers in the factories is another contributing factor, as is time spent by colleagues in communal spaces such as in locker rooms and on shuttle buses.
Research by the London School of Hygiene and Tropical Medicine showed that food production facilities had been responsible for a relatively high number of localised outbreaks, as well as ships and workers’ dormitories.
It said: “It is possible that the cold atmosphere in this setting has facilitated the spread of the virus. Other possible explanations include the close proximity of workers for prolonged periods, shared welfare spaces, as well as the need to speak loudly to communicate over the noise of the machines, which could lead to an increased projection of viral particles.”
A Guardian analysis last month found that almost half of the Covid-19 hotspots in the US were linked to plants where poultry, pigs and cattle were slaughtered and packaged. The outbreaks led to calls for urgent reforms to an industry beset by health and safety issues.