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The government has outlined plans for the British to test for antibodies to the coronavirus at home, with finger-stick kits to be made available on Amazon and Boots.
But what are these tests? – and they work?
What is an antibody test?
An antibody test can detect whether a person has had a coronavirus before and has since recovered. The test, carried out by a device that pricks the blood from your finger, solves it by analyzing your blood for antibodies against the coronavirus to see if they have already defeated the virus and given it some immunity. You can do this in about 15 minutes.
The coronavirus swab test that the government currently uses can only tell if a person has the virus, not if they have had it and have recovered. These swab tests also take much longer to obtain a result.
The antibody test is also known as a “serological test.”
The government hoped to launch millions of antibody tests in the coming weeks, but supplies from China have so far failed the sensitivity and specificity tests.
The ministers will try to recover taxpayers’ money spent on fingerstick tests after an Oxford University trial found that they yielded inaccurate results.
The failure is a significant setback because antibody tests were expected to show who had already built up immunity, thus offering a faster route out of the blockade.
Earlier this month, however, Professor Karol Sikora, a private oncologist and dean of medicine at Buckingham University, validated a test kit with samples from staff at his clinics, which were then verified by a private laboratory.
About six percent of staff were found to have the virus, but more importantly, those younger than 40 who tested positive tested positive, suggesting that the test may not be useful to the general population.
Siemens Healthineers, a German medical imaging and diagnostic firm, also announced on April 23 that it is producing a blood test for antibodies to identify previous coronavirus infections.
Blood tests will be available to large labs in late May, the company said, adding that it will be able to provide more than 25 million tests per month starting in June thanks to an update from its manufacturing site in Massachusetts.
According to Professor John Newton, the UK’s national testing coordinator, another antibody test that was started by the University of Oxford in late May may be available.
What is an antigen test?
An antigen test detects the presence (or absence) of an antigen, not of antibodies. An antigen is a structure within a virus that triggers the immune system’s response to fight infection. It can be detected in the blood before antibodies are produced.
An antigen test is effective because it can take a few days for the immune system to generate enough antibodies to be detected in a test, however, antigens can be detected almost immediately after infection. So in theory the test can determine much earlier if someone has the virus.
Antigen tests are used to diagnose HIV, malaria, and the flu.
