John Lewis will be one of the first big store chains to offer free almost-instant Covid tests to its workers.
It will make rapid testing available at 40 of its sites, including a factory, warehouses and some high street shops.
Up to 16,000 workers will be voluntarily tested every week and its success could lead to other retailers adopting the NHS-linked scheme.
But a shopworkers union warned that staff testing positive needed support from their employers.
“We expect employers to ensure that staff understand how testing will work, what the results mean and to support those who are ill, self-isolating or shielding on full pay,” said a spokesman for the Union of Shop Distributive & Allied Workers.
The NHS Test and Trace lateral flow Covid tests are conducted at a dedicated testing site by trained staff with results available within 30 minutes.
Testing is voluntary and will be carried out in a temporary room up to three times a week where workers take a swab from their throat then hands it to an NHS-trained John Lewis staff member.
The scheme was piloted in November at the store chain’s distribution centre in Milton Keynes.
“We’re proud to have helped develop and establish a testing scheme,” said John Lewis executive director for operations Andrew Murphy
Dido Harding, the interim executive chair of the National Institute for Health Protection and head of the NHS test and trace programme, said: “This pilot is one of many which will lay the foundations for the next phase of NHS test and trace with rapid, targeted testing which will allow us to identify even more people who may be unknowingly carrying the virus, more quickly.”
She added that testing is taking place in hospitals, care homes, universities “and other areas that we value”.
Other business have adopted different approaches to offering staff regular testing.
Online retailer Amazon has set up its own testing labs for its workers, including one in Manchester.
“Providing regular testing for our employees allows us to identify asymptomatic cases who might not otherwise be tested,” said Antoine Dreyfus, former director of Amazon devices in the EU, who is now leading Amazon’s UK testing project.
Engineering giant BAE Systems has used a private lab to do in-house mass testing of its 8,000 employees at its shipyard in Barrow-in-Furness, Cumbria, where it makes the Royal Navy’s submarine fleet.
Weekly tests are offered using a technology known as RT-LAMP.
“It’s very fast and very sensitive,” Chris Stanley of Circular1 Health, which provides the service, told New Scientist magazine.
“We have recently published a list of approved private providers of Covid-19 testing, to help employers access the services they need to carry out testing and identify the virus among their staff,” said Health Minister Lord Bethell.