Coronavirus antibody tests will be available on the NHS following agreements between the government and pharmaceutical firms Roche and Abbott.
Health Secretary Matt Hancock said the government has signed contracts to supply 10 million antibody tests - which show if someone has had COVID-19 and potentially developed immunity to the virus.
The rollout will start with health care workers, patients and care home residents from next week.
He told the government's daily briefing: "The UK government has arranged supplies of these tests on behalf of the devolved administrations and each devolved nation is deciding how to use its test allocation and how testing will be prioritised and managed locally.
"This is an important milestone and it represents further progress in our national testing programme."
Earlier, the prime minister's spokesman said the tests will be "free for people who need them, as you would expect".
At the briefing, Mr Hancock added that the government could not currently say if people who test positive for these antibodies are necessarily immune from COVID-19.
But, he said the insight they provide is crucial to understanding how people's bodies react to coronavirus and how it is spreading across the country.
He said the government had done an "antibody surveillance study" which revealed about 17% of people in London, and 5%, or higher, in the rest of the country have tested positive for having coronavirus antibodies.
"But, for the public at large to know whether or not they have antibodies we need antibody tests at a larger scale," the health secretary added.
As well as the two tests from Roche and Abbott, Mr Hancock said three more are being assessed and he ultimately wants a "home-grown" antibody test which he said is "showing some early promise".
Mr Hancock also announced 338 more people have died with the virus, according to the Department of Health, taking the total to 36,042.
Across the four nations:
The discrepancy between the total UK figure and the individual home nations is due to each authority calculating their deaths in different ways and at different times.
The coronavirus antibody blood tests, made by Swiss pharmaceutical firm Roche and US firm Abbott Laboratories, were given approval by Public Health England on 14 May after scientists at its Porton Down facility found the test was "highly specific" and had an accuracy of 100%.
England's deputy chief medical officer, Professor Jonathan Van-Tam, last week promised the tests would be rolled out "rapidly".
He cautioned it could take up to 28 days after someone is infected before the test can properly confirm if a person did have the virus.
It will "take time" to monitor how much people with antibodies have immunity from the virus and how long it could last for, he explained.
The tests were heralded by Prime Minister Boris Johnson as being a "game-changer" for lifting lockdown because someone who finds out they have antibodies can be "safe and confident in the knowledge that you are most unlikely to get it again".
But John Edmunds, professor of infectious disease modelling at the London School of Hygiene and Tropical Medicine, has warned studies of other coronaviruses suggest "potentially bad news" for hopes humans could develop a long-term immunity.
He told a parliamentary committee on Tuesday: "We can also see from other coronaviruses, from ones that cause coughs and colds, that individuals again do seem to not have particularly long-term immunity to many of those viruses, allowing them to get reinfected later.
"Immunity may not last that long against this virus."
A report prepared by the government's top scientific advisers also warned if antibody tests come into widespread use some employers might start discriminating against those who haven't had the virus.
"This might include not permitting those testing antibody negative to return to work, or only taking on new staff with antibody positive test results," their paper compiled in mid-April cautioned.