Sainsbury said its plans were based around a number of scenarios, including speculation that one in four people could fall ill.
A spokeswoman said: “We’ve identified areas of risk, such as distribution, supply, colleague shortages, and will implement plans if and when required.”
Sainsbury is also making plans to cater for higher demand of the types of products people buy when ill, such as painkillers, soup and store cupboard foods.
Tesco and Asda said they were also in the process of drawing up plans to cope with a potential outbreak.
Scientific assessments of Britain’s ability to continue feeding itself if a flu pandemic hits will be delivered to the government by Cranfield University within three months.
They will include estimates of the ability of retail outlets and networks to keep functioning. It follows forecasts that crucial systems could collapse, causing food shortages.
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