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Explains antibody testing for COVID-19 including that it cannot tell people whether they are immune.

First published:
29 June 2020
Last updated:


COVID-19 antibody testing measures the amount of COVID-19 antibodies in a blood sample.

This can tell us whether a person has previously been infected with coronavirus or has been vaccinated. 

Antibody tests are able to detect two different types of antibodies:

  • ‘n’ antibodies (necleocapsid) which appear after an infection
  • ‘s’ antibodies (spike antibodies) which appear after an infection or vaccination

Antibody tests were first used to find out whether a person had already had the virus and helped us understand how the disease was spreading. They can now also tell us if someone has had a coronavirus vaccination.

The value of antibody testing

Antibody testing can tells us:

  • how many people have had the infection
  • how far and wide the virus has spread
  • how many people have been vaccinated

There is currently not enough evidence on how well COVID-19 antibodies are at:

  • fighting the virus
  • protecting you from getting it again
  • stopping transmission to others

We also don’t know how long antibodies from the infection will last.

Research is ongoing to find the answers to these questions.

Antibody testing in Wales

Antibody testing is carried out in several areas.


Some people may be offered a test for antibody research studies.

People who have tested positive for COVID-19 may be asked to opt into antibody testing as part of the Post Positive PCR Antibody Testing Initiative (PPPATI). More information can be found on the UK Government website.

This study looks at how antibodies from infection or vaccination differ across groups of people and over time. This will help to understand how long infection and vaccination can give protection. 

People who book a PCR test will be asked if they are willing to take part in this study. If they opt in, they will need to take 2 antibody tests if their PCR test is positive. Opting in is voluntary and will not affect the way PCR tests are managed. 

It will show the differences in antibody levels between getting the infection and some time after the infection. Not all who opt into the offer will be offered a test.


Your doctor may ask you to take an antibody test for medical reasons.

Office of National Statistics

The Office of National Statistics also tests random samples of the population for COVID-19 antigens. This provides a picture of the prevalence of COVID-19 in the UK population. We publish statistics for Wales every month.

Health and social care staff

In 2020 antibody testing was conducted on some healthcare, social care and education workers to help us understand if and how they got the virus. These people now have regular COVID-19 tests and are being vaccinated. This means we do not need to continue antibody testing.