Tests for healthcare workers will be rolled out next week, allowing them to confirm whether they have been infected or are safe to work, the government has announced.

Michael Gove – standing in for the prime minister at the daily briefing after Boris Johnson was diagnosed with Covid-19 – said the testing was being trialled immediately, and that hundreds were expected to be able to access the tests over the weekend. The country would see a “dramatic” increase in testing next week, he added.

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“Increasing our testing capacity is absolutely crucial in our response to and our fight against coronavirus,” said Gove. “This is a particular priority for those who work in the health and social care sector and are working so hard to keep us all safe.”

The increased testing capacity will be delivered by an alliance that includes Thermo Fisher Scientific, Amazon, Boots, Royal Mail and Randox, alongside the Wellcome Trust and leading universities. The antigen tests spot viral proteins in the blood and are a much quicker way of identifying whether someone has an infection. For other infections the tests can give an answer in less than an hour.

Antigen tests are different from the antibody tests that the government said it plans to roll out as early as next week. Antibody tests are not diagnostic; they reveal whether a person has previously had an infection after they have recovered.

Sir Simon Stevens, chief executive of the NHS, said: “It is urgently important to test frontline staff who are off sick or are self-isolating. The number of tests carried out will be doubled by the end of next week compared to this week.”

In another announcement which also underlined the pressure on the NHS, Stevens said two further NHS Nightingale hospitals would be opened amid efforts to turn London’s ExCel centre into a facility that can hold up to 4,000 beds. One, based at the NEC in Birmingham, will start with up to 500 beds equipped with the capacity to increase up to 2,000 if needed. The other, based at the Manchester Central convention complex, will provide up to 500 beds but could expand to 1,000.

The tests for NHS employees will start with critical care doctors and nurses and other intensive care staff, as well as those in emergency departments, ambulance services and GPs. Stevens said the service would be expanded to a range of essential public workers, including those in social care services, as testing volumes increased.

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The government has come under increasing pressure in the past week to make testing available to healthcare workers. Chaand Nagpaul, chair of the council of the British Medical Association, told parliament’s health and social care select committee on Thursday that “large numbers” of NHS staff were off work already with coronavirus symptoms, leaving hospital departments and GPs with serious staff shortages as the demand for care continues to rise.

Chris Hopson, chief executive of NHS Providers, told the Guardian this week that the challenge of coping with a surge in patients in London hospitals had been exacerbated by medical staff being off with suspected coronavirus or in vulnerable groups, with 30% to 50% not at work in some trusts.

Without widely available testing, staff in hospitals have had to self-isolate if they or anyone in their household have Covid-19-like symptoms, including a cough or fever, even though they might not have the virus. The new testing regime would address this problem, Gove said, giving people the knowledge that they are safe to return to work if they test negative.