Frozen food specialist Iceland has revealed that more than one in 10 workers are currently self-isolating as staff shortages take a toll on business, the NHS, and public transport networks after the Christmas break.

The supermarket chain told Sky News that about 3,300 people were currently at home – representing 11% of its entire workforce – as rules to stem the spread of the Omicron variant add to disruption.

Iceland said the rates of staff absence in recent days were more than double last year’s peak during the so-called “pingdemic”, when users of the NHS COVID app identified as coming into close contact with someone who had tested positive had to isolate for 10 days.

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The company, which had reported “strong sales” in the run-up to Christmas, said it closed two stores on New Year’s Day to spread available shop workers around.

It spoke up as the wider grocery sector – credited with feeding the nation during lockdown conditions since March 2020 – voiced fears that shoppers could face difficulties if the isolation situation deteriorated.

Helen Dickinson, chief executive of the British Retail Consortium which represents the chains, said: “Staff absences continue to rise in line with rising COVID cases, however the overall situation remains manageable throughout the supply chain.

“Retailers are monitoring the situation closely – clearly, continued rising absence rates due to self-isolation will get increasingly difficult to sustain.”

As a growing number of hospitals warn about services, staff absence rates on Britain’s railways are running at around one in 10.

An average of about one in 20 services was cancelled over the last fortnight, according to the train firm industry body the Rail Delivery Group.

Guidance which means people should work from home if they can is easing some of the pressure on services.