Thousands of adults every day will be given free access to antibody tests through a new national surveillance programme.

The government scheme is aimed at better understanding immunity against Covid-19 from vaccination and infection.

For the first time, the UK Health Security Agency programme will offer antibody testing to adults in the UK who test positive.

From Tuesday, anyone aged over 18 will be able to opt in to take part when booking a PCR test through NHS Test and Trace. Up to 8,000 people who opt in and then receive a positive PCR result will be sent two finger prick antibody tests to complete at home and send back to a lab for analysis.

The UK Health Security Agency will work alongside NHS Test and Trace testing services in England, Scotland, Wales and Northern Ireland to monitor levels of antibodies in positive cases across the UK. The data collected will help estimate the proportion of those who got COVID-19 despite developing antibodies as a result of having a vaccine or previously catching coronavirus.

The initiative could also provide insight into any groups of people who do not develop an immune response. The UK Health Security Agency will use the data to inform our ongoing approach to COVID-19 and provide further insight into the effectiveness of the vaccines against different variants.

Sajid Javid, secretary of state for health and social care, 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."

All adults interested in the study are encouraged to opt in. Anyone taking part must take their first antibody test as soon as possible after receiving a positive PCR result, before the body has had time to generate a detectable antibody response to the current infection.

The first test will determine the level of antibodies a person had before their current infection.

The second test should be taken 28 days after testing positive for Covid-19 and will measure antibodies generated in response to the infection.  By comparing the two antibody test results, the UK Health Security Agency will be able to see how well vaccinated individuals boost their immunity when they are infected and how this might vary with different variants.