Superdrug has been forced to pull its coronavirus antibody test over concerns about the reliability of test results. It had become the first high-street retailer to offer a test last week, charging £69 for it.
However, the Medicines and Healthcare products Regulatory Agency (MHRA) has since issued a warning urging providers of this specific test to suspend sales, telling anyone who has bought a test previously not to trust the results.
'Patient safety and public health are our main priorities — and it is in the interests of everyone for antibody tests to be as reliable and meaningful as they can be,' Graeme Tunbridge, director of devices at the MHRA, said in a press release.
'We are asking all providers of laboratory-based Covid-19 antibody testing services using capillary blood collected by a finger prick to temporarily stop providing this service until home collection of this sample type has been properly validated for use with these laboratory tests,' he continued. 'Use of unvalidated sample types may lead to unreliable results and as such we are working closely with the service providers, laboratories and test manufacturers to resolve the regulatory and patient safety issues.'
This means those who spent £69 purchasing a test last week should now consider those results invalid.
'People who have purchased one of these sampling kits, and received an antibody test result, should not consider the result to be reliable and should not take any action on it,' Tunbridge said. 'This does not affect rapid point-of-care tests or laboratory tests performed using venous blood.'
This means that the MHRA warning does not apply to antibody tests using blood obtained from the veins, which requires a healthcare professional to administer.
Other UK providers of the finger prick test include Lloyds Pharmacy and the private GP service Doctorcall.
What is an antibody test?
Antibody tests detect if someone has had Covid-19 in the past and since recovered. Currently, there are two types of tests being examined. One is a venous test where blood is taken from the veins by a healthcare professional. In the Elecsys laboratory-based test, reagents are added to the blood serums and then examined in machines known as cobas e analysers, already widely installed in NHS labs across the country.
Another type of antibody test is performed via finger prick, to draw blood that is then sent off to a laboratory for examination, and can be done at home. The finger prick tests were the ones being offered by Superdrug and other pharmacies, however Public Health England has only approved the venous tests so far.
The theory with antibody tests is that if you’ve beaten the virus, you may have gained some immunity to it.
It’s what the government was relying on earlier this year in order to ease lockdown enough to get people back in work, spending millions on a test from China that was eventually found to be inaccurate by Oxford University. The setback means that various other antibody tests are still being evaluated before they can be offered on the NHS.
How did the Superdrug antibody test work?
According to a press release from the firm, a blood sampling kit was sent in the post. There are detailed instructions about how to carry it out with a simple finger prick using a lancet (similar to how diabetics test their sugar levels). A few drops of blood need to be collected into a small vial, secured in the packaging and posted to the UKAS-accredited lab using the pre-paid packaging. The results were then available from Superdrug Online Doctor within 24 hours of the sample reaching the lab.
A spokesperson for Superdrug has since stated that the company are 'contacting all our Covid-19 antibody testing service customers today to provide further information about the quality and safety of our Covid-19 antibody laboratory-based testing service'.
How reliable are antibody tests?
Public Health England approved a number of venous antibody tests earlier this month created by Roche and the Government has since ordered 10 million of them.
However, they have only approved venous tests, not finger prick antibody blood tests, leading some online providers to have wrongly claimed that their kits are 'PHE validated', according to The Telegraph.
The PHE does not yet regard tests on blood samples taken from the capillaries on the end of the finger as effective.
As well as experts warnings about the accuracy of the test, there have also been questions raised of what immunity even means.
Dr Ron Daniels, a consultant in critical care at University Hospitals Birmingham NHS Foundation Trust, told The Telegraph that scientists just don’t know how long immunity will last or how immune you may be, even if you are proven to have beaten Covid-19. He guessed immunity means someone may be ‘partially protected for at least a few months’ but warned such people not to stop social distancing as scientists cannot know for sure as of yet.
‘I would caution against using any tests... without knowing quite how good those tests are,’ NHS England's medical director Prof Stephen Powi told the BBC.
'The Superdrug test has a sensitivity of 97.5%,' a representative for Superdrug said in a press release last week prior to the test being pulled. 'This means that it will detect positive antibodies 97.5% of the time. A small number of previous infections might go undetected.'
This test isn't the first to be approved and then later questioned. Most notably, the UK government spent millions in March on a test from China only for Oxford University to examine them and find they were inaccurate.
Is there an NHS antibody test?
According to the BBC, health officials in England have approved an antibody test that will be rolled out to the public via the NHS soon. Health Secretary Matt Hancock confirmed they are in ‘the closing stages of commercial negotiations’ this week. Professor John Newton, who is the UK’s national testing co-ordinator, has previously stated it should be available by the end of May.
The managing director of healthcare company Roche Diagnostics UK and Ireland, Geoff Twist, said his firm was working with the government and the NHS to allow the company's test to be rolled out across the UK as soon as possible.
How can I get an antibody test?
Private clinics have been offering home antibody tests for months, but Superdrug became the first high-street retailer to offer Covid-19 antibody tests, costing £69. However, with these finger prick tests now being recalled, many will wait until the venous antibody test is rolled out to the public. Current reports state that once the government begins the antibody tests, they will first only be available in hospitals and care homes.
Can I see family and friends after having an antibody test?
Given the caution around the reliability of the tests and what immunity means, experts are still warning that those who take antibody tests and discover that they have had Covid-19 should continue to practise social distancing.
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