A finger-prick test for Covid-19 antibodies being bought by the government is considerably less accurate than claimed by the company that makes it, a formal evaluation by Public Health England has found.
On 6 October the health minister James Bethell announced the government had bought 1m of the tests, even though the Department of Health and Social Care (DHSC) had by then seen the evaluation report from PHE.
Abingdon Health, the company making the test, claimed it was 99% accurate. But a PHE report, published on Thursday in the British Medical Journal (BMJ), says the test can confirm 92.5% of cases already known to be positive. But in real-world conditions, the accuracy falls to 84.7%.
It means that if 10% of people given the test had previously been infected, about one in five positive test results would be incorrect, ie false positive results.
The department says the tests are still useful for surveillance – finding out what proportion of communities have been infected with the virus in the past. In an editorial in the BMJ, two experts, Dipender Gill from Imperial College London and Mark J Ponsford from Cardiff University, said the company had overestimated the test’s accuracy due to the manner in which its trials were carried out and that it should not be widely used.
The PHE study “identifies notable limitations of the UK government’s antibody test of choice and provides good evidence that its specificity in a ‘real life’ setting is highly unlikely to be 100%. Apart from limited surveillance to estimate the proportion of a population that has been infected, widespread use of this assay in any other role could risk considerable harm,” they write.
Emails seen by the Guardian show that the DHSC blocked online publication of the results at the time of the ministerial announcement. PHE said there were “significant risks” to delaying publication because the findings were out of line with the claimed accuracy of the tests.
DHSC officials denied they blocked publication, saying they preferred to go down the route of peer review.
The PHE assessment is acutely embarrassing for ministers who put together a British consortium to make an antibody test for the UK in the spring, with Abingdon Health in the lead. Also in the consortium was Oxford University. Sir John Bell, regius professor of medicine at Oxford and the government’s life science adviser, helped put the consortium together, although he played no part in the development or assessment of the test.
Lawyers for the Good Law Project have filed proceedings against the government over the awarding of two contracts for the antibody tests to Abingdon Health without putting them out to tender. One was worth £10m and the other up to £75m.
The government cited a need for urgency because of the pandemic – it was developed after the failure of Chinese antibody tests bought by the health secretary, Matt Hancock, in the spring. But the lawyers argue that other tests existed at the time. They also say the government failed to ensure the tests were of high enough quality before agreeing the deals.
Emails seen by the Guardian show a discussion between the DHSC and PHE about the handling of Lord Bethell’s announcement on 6 October that the government had bought 1m tests from the consortium.
PHE staff said there were “significant risks” in not publishing the evaluation showing the low accuracy of the tests at the same time as the announcement. The Guardian was already asking for the data, it pointed out, having run stories questioning the claim by the company that the tests were 99.4% accurate.
In an email, PHE asked whether this strategy had been agreed. “Is everyone aligned on the handling – ministers, spads etc?” it asked.
The reply from the DHSC ran: “Yes everyone is aligned as far as I know. L Bethell aligned, No 10 now aligned.”
PHE had suggested the evaluation could be published online at the same time as the announcement as a preprint, the emails reveal. But this was blocked by the DHSC. PHE’s team therefore submitted it to the peer-reviewed BMJ, beginning a process that would take weeks.
The DHSC said the plan was for “minimal mention” of the PHE study in Bethell’s announcement, “but we do need to mention it as we will get asked”. In a further email it suggested a way to deal with questions as to where the results of the study were: “If asked tomorrow, we can say that we’ve submitted to BMJ for peer review so we are being transparent.”
The DHSC said it was inaccurate to say it delayed publication, pointing out that the PHE evaluation was sent to the BMJ for peer review in early October in line with standard procedure for academic reports.
Two government contracts were awarded to the consortium, according to documents in the public domain. The first, in June, was for the consortium to buy components for making the tests and was worth £10m. The second was in August and gave the government an option to buy the tests, worth £75m.
In March, there were high hopes for antibody tests, commonly described as potential gamechangers. Ministers and their advisers envisioned the tests being dispatched to people at home by Amazon or bought on the high street. The expectation was that individuals could find out if they had had coronavirus and were immune. There was talk of giving those who tested positive “immunity passports” to allow them greater freedoms, on the assumption they were no longer at risk of infection. It is now widely accepted that antibodies fade and do not necessarily confer immunity from Covid-19.
In his announcement last month, Bethell said: “Home testing is a powerful tool in understanding the disease and fighting its spread. So we are thrilled by the RTC [Rapid Test Consortium] product, both for Britain and export markets around the world.”
The tests developed and made by British companies “demonstrate how, supported by government investment, the UK diagnostics industry is leading on the global stage in our efforts to tackle Covid-19”, said the release.
The DHSC said in a statement: “The antibody test has been evaluated by PHE and this evaluation will be published in due course. This [PHE] report shows these tests are approved for use in surveillance studies, which is what they were purchased for.
“They were never intended for, and have never been issued for, widespread public use and it is misleading and unnecessarily inflammatory to purposefully ignore this fact in the report. This robust evaluation was carried out by PHE at the department’s request before any purchase was made, and PHE approved the test for use in surveillance studies.”
Abingdon Health declined to comment, saying questions were best answered by the DHSC, which was happy with the test.