Frontline NHS staff in England will start being tested this weekend to see whether they have coronavirus.
Workers with symptoms or those who live with people who have symptoms will be checked – starting with critical care doctors and nurses.
It follows criticism over a lack of testing for health workers.
Meanwhile, the prime minister and Health Secretary Matt Hancock are self-isolating after testing positive for the virus.
Boris Johnson, 55, said he had experienced mild symptoms over the past 24 hours but would continue to lead the government’s response to the pandemic while working from his Downing Street home. Mr Hancock said his symptoms were also mild and he was working from home.
The number of people who have died with the virus in the UK rose by 181 to 759 on Friday, with 14,543 confirmed cases.
Hundreds of frontline NHS staff are to be given antigen tests – to check whether they currently have the disease – this weekend, with the government promising to scale testing up “dramatically” next week.
Testing of ambulance crews, paramedics and GPs is expected to follow and this will later be expanded to cover social care staff.
In Wales, frontline NHS staff are already being screened for the virus, while Scotland’s chief medical officer has confirmed a protocol for testing “significant” figures.
Northern Ireland plans to increase testing to 1,000 a day from next week.
Analysis suggests the rate of infection in the UK has been doubling every three to four days, Cabinet Office secretary Michael Gove said on Friday.
Experts expect cases to continue to increase over the next two to three weeks, before the effects of social distancing measures and restrictions on everyday life begin to have an impact.