This is what happens when you are selected for a random antibody test for coronavirus to determine if you've unwittingly had the virus without symptoms.
The research is being run by doctors and researchers at Imperial College London, research company Ipsos Mori and funded by the Department of Health and Social Care.
Participants are chosen because they registered to take part in response to an initial invitation letter. The initial invitation was sent out after being randomly selected from the Post Office's list of addresses in England, which people will have responded to.
They then get sent the home antibody kit to test themselves. People must read the instructions of the self-test antibody kit and perform the test "on yourself at home."