Watch Caron Bell's report
5,000 Bristolians are taking a test to find out if they have had coronavirus without realising.
The volunteers, all part of a Bristol University study, will use a home finger-prick test to see if they have Covid-19 antibodies in their blood.
Although having antibodies does not guarantee you immunity from future infection, it does mean you have probably had the virus, and gives scientists useful data about how Covid is spreading.
The test kits are being sent to participants of ‘Children of the 90s’ - a Bristol University programme that has been tracking thousands of children born in Bristol in the early 1990s, and their families, since birth.
It has already informed 2000 research papers on major issues like childhood obesity, air pollution and mental health.
It is the most detailed study of its kind in the world and, in the current crisis, the depth of its research could be especially useful.
The study will continue to track the volunteers in years to come, and so could provide useful information about how Covid affects them in the future - in particular the emerging long term effects known as ‘Long Covid’.
The number of antibody tests being done in Bristol is unusual. At the moment, they are not widely available to the general public. In England, the Government is only offering them to those aged 18 and over who work in paid adult social care, although you can buy one privately.