A high street retailer has become the latest to offer a DIY kit to test for Covid-19 antibodies.
Superdrug is the first high street retailer to offer a Covid-19 antibody test.
The testing kit costs £69 and users need to take a blood sample at home which is sent off to an accredited laboratory for testing.
But some experts have urged caution over the test, with one saying that antibody tests for Covid-19 are “good for satisfying people’s curiosity but no more”.
People who use the test will need to take a finger prick blood sample at home and then post the sample off to a lab.
Results are posted through Superdrug’s Online Doctor portal 24 hours after reaching the lab.
Superdrug said it was “confident” in the accuracy and reliability of the test.
It said that the test detects the IgG, which is the protein that develops after infection. If positive, it means that the person tested had the virus at some point.
Those who have recently developed symptoms should not take the test until at least 14 days as the antibodies may not be apparent before that point, it added.
Superdrug said the test has a sensitivity of 97.5%, which means that it will detect positive antibodies 97.5% of the time.
It has a specificity of 100%, which means that a positive result is specific to the SARS-CoV-2 virus – the novel coronavirus which causes the Covid-19 disease.
Receiving a positive antibody test result does not confer immunity, and it is important that people understand a positive test result does not mean you can be any more relaxed with the required hygiene and social distancing measures as set out by the GovernmentDr Zoe Williams, Superdrug's doctor ambassador
But the science behind the level of protection provided by antibodies is still in its early stages – the virus has not been around long enough to know what level of protection any antibodies give.
Indeed Superdrug’s doctor ambassador, Dr Zoe Williams, said: “Receiving a positive antibody test result does not confer immunity, and it is important that people understand a positive test result does not mean you can be any more relaxed with the required hygiene and social distancing measures as set out by the Government.”
Commenting on the availability of the test from Superdrug, as well as one released by healthcare company Babylon for the same price, Dr Simon Clarke, associate professor in cellular microbiology at the University of Reading, said: “When someone falls ill with Covid-19, their immune system generates a range of antibodies which recognise various bits of the coronavirus.
“It’s not yet known which, if any, of these protect us against subsequent infection, but having these antibodies is a reliable way of confirming that someone has been infected previously.
These tests are good for satisfying people’s curiosity, but no moreDr Simon Clarke
“Their presence does not indicate that someone is immune and it should be remembered that any post-infection immunity may dwindle rapidly.
“These tests are good for satisfying people’s curiosity, but no more. We just don’t know enough about what it takes to make someone immune to Covid-19 to accurately test people.”
Martin Hibberd, professor of emerging infectious disease at the London School of Hygiene and Tropical Medicine, said: “These new at-home tests promise to be quite popular, as people who have not had the opportunity to be tested wonder if they have had the disease.
“However, these tests have not been evaluated in the format that they are being used (finger prick at home and posting to a laboratory for reading) so we cannot yet be confident in their sensitivity and specificity.
“Despite this, I am pleased to see that the process includes a laboratory approach to reading the test, which should reduce the errors associated with doing this at home. And of course, a finger prick test at home is easier than visiting a clinic to give a more regular blood sample.
“The problem with these tests will come with their interpretation in the wider context of preventing Covid-19 and SARS-CoV-2 transmission. A positive result shows that you have had the infection, but we do not yet know how likely that means you are to be protected from future infections, or how long those antibodies will last.
“And, of course, even if protected, you may still be able to transmit the disease by spreading the virus from one surface to another, for example by touching door handles. People using this test will need to interpret the result with caution and still follow guidelines on transmission prevention.”
Professor Gino Martini, chief scientific officer at the Royal Pharmaceutical Society, added: “Any antibody test at present can only provide a partial picture. The real issue is that no-one knows the level of immunity that is conferred by having antibodies to coronavirus, how long it might last, and if you can become re-infected. We need much more information and data on immunity before we can understand the importance of having antibodies to the virus.”
Previously, experts have urged consumers to check the specificity and sensitivity of any tests to ensure they are accurate at detecting antibodies for the novel coronavirus.