Wide availability of Covid-19 antibody testing was once billed as a key exit route from lockdown. The purpose of the antibody test is to determine whether an individual has previously contracted coronavirus and recovered, meaning that there is a possibility of immunity. Understanding the path that the virus has taken was, therefore, seen as a major part of getting the UK back to work.
The antibody tests are not like the existing coronavirus swab tests being widely used by the government, which can only determine whether an individual has the virus at the time of testing. Swab tests also take longer amounts of time to return results than the antibody blood tests.
However, Superdrug, which became the first high-street retailer to begin offering home Covid-19 antibody tests, suspended sales of the test in May after health regulators issued warnings over its reliability.
The Superdrug testing kit initially went to market at a price of £69 and users take finger prick blood samples at home which are then forwarded on to accredited laboratories to be tested. Similar testing kits are available through other websites including that of Lloyds Pharmacy, according to the Telegraph.
The Medicines and Healthcare products Regulatory Agency [MHRA] first appealed for the sale of such tests to be stopped in May, warning that people who have used the finger prick antibody tests “should not consider the results to be reliable” nor “take any action” based on the outcome of the test.
Indeed, Dr George Xynopoulos, founder and CEO of private North London clinical pathology laboratory Medical Diagnosis warned earlier in the year that the development and mass production of a reliable antibody test would take time.
Speaking to Sky News in April, Dr Xynopoulos said: “Everything in medicine takes time, it is not something you can do by waving a wand, so it needs proper verification and it needs trials.”
The exact issue with the home-antibody testing kits to date is that Public Health England does not yet regard blood samples taken from the capillaries at the end of the finger as an effective specimen.
The government had initially ordered some millions of these tests from China back in April, before trials undertaken at the University of Oxford revealed that they were largely inaccurate and unsuitable for public use.
Furthermore, Professor Karol Sikora, private oncologist and Dean of Medicine at the Unviersity of Buckingham, took samples from his own staff members using the test, with results subsequently verified by a private laboratory. Professor Sikora’s samples revealed that some under-40s who were known to have had the virus returned negative antibody test results, suggesting a further lack of reliability.
Prof Sikora said at the time: "I think the antibody tests do work – but young people just don't seem to have the antibodies, which suggests they are using other mechanisms to fight off the virus.”
The unreliable finger prick tests are unlike the venous antibody tests which were first manufactured by Swiss firm, Roche, and granted Public Health England approval back in May.
The Roche tests have been deemed reliable by the MHRA because blood samples are taken from the veins, making them more reliable, and require a health professional to administer them. The government ordered ten million of them after they were approved.
A discrepancy concerning the finger prick tests lay in the fact that they utilise the same technology as the venous test produced by Roche, prompting online retailers to mistakenly advertise the home-testing kits as PHE approved after the Roche tests were allowed to go to market.
Even with the recent breakthrough of a reliable test of any kind, the levels of immunity that can be expected of individuals who have previously had the virus and beaten it also remains unclear.
Dr Ron Daniels, a consultant in critical care at University Hospitals Birmingham NHS Foundation Trust, said: “If you test positive for antibodies, it’s likely you have a degree of immunity. We’re not sure for how long, and how much, so you shouldn’t stop [social] distancing, but best guess it is likely to be partially protective for at least a few months.”
With the only reliable antibody test thus far requiring the presence of a health professional and uncertainties remaining over the levels of immunity that can be expected, it is likely that mass production of a home antibody testing kit is some way off, even with molecular tests currently in development ahead of the autumn.