Antibody tests are to be widely offered to the UK public for the first time in a new programme that aims to find out more about how much natural protection people have after getting coronavirus.
Anyone over 18 will be able to opt in when having a PCR test from Tuesday - of those who test positive, up to 8,000 will be sent two home antibody tests.
Health Secretary Sajid Javid said it would be quick and easy to take part, BBC reported.
The first of the finger-prick tests would have to be done as soon as possible after the positive result, so the body would not have time to generate a detectable antibody response to the infection.
The second would be taken 28 days later and measure antibodies generated in response to the infection.
The UK Health Security Agency is to run the programme and will work alongside NHS test and trace services in England, Scotland, Wales and Northern Ireland to use results to monitor levels of antibodies in positive cases.