Thousands of adults a day will be given free access to tests through a new national surveillance programme launched by the UK Health Security Agency next week.
From Tuesday, August 24, anyone aged over 18 will be able to opt to take part when booking a PCR test through NHS Test and Trace.
Up to 8,000 people who test positive will then be sent two finger prick antibody tests to complete at home and send back for analysis.
The agency will monitor levels of antibodies to help estimate the proportion of those who got Covid-19 despite developing antibodies as a result of having a vaccine or previous infection.
The initiative could also provide insight into any groups of people who do not develop an immune response.
Health Secretary Sajid Javid said: “Our new national antibody testing will be quick and easy to take part in, and by doing so you’ll be helping strengthen our understanding of Covid-19 as we cautiously return to a more normal life.
“I’m proud to see all parts of the UK uniting around this new initiative and working together to arm ourselves with even more valuable insights into how Covid-19 vaccines are protecting people up and down the UK.
“I urge everyone across the UK to get both vaccinations as soon as possible.”
Anyone taking part must take their first antibody test as soon as possible after receiving a positive PCR result, before their body has had time to generate a detectable antibody response to the latest infection.
The first test will determine the level of antibodies a person had before their current infection.
The second test should be taken after 28 days and will measure antibodies generated in response to the new infection.
Comparing results will show how well vaccinated individuals boost their immunity when infected and how this might vary with different variants.
Testing positive for antibodies does not mean someone is immune from Covid-19 and people must continue to follow the rules, get tested if they have symptoms and self-isolate if positive or are a contact of a positive case and have not received both vaccine doses, to prevent the virus from spreading.