Senior medical specialists have raised concerns about the accuracy of the antibody tests being carried out on NHS staff across the country.
The blood tests – which can tell whether someone has had Covid-19 – were previously described by prime minister Boris Johnson as “game-changing”.
The government has spent £16m buying some 10 million test kits from pharmaceutical giant Abbott and Roche with the first phase of the testing programme assessing NHS and care staff, before being rolled out to the public.
But a letter from academics and clinicians, published in The BMJ, raises concerns about the performance of the tests, the clinical reasoning for them and the cost.
“We are writing to express concerns over aspects of the establishment of SARS-CoV-2 antibody testing in England,” the team of experts wrote.
“NHS England and NHS Improvement wrote to NHS trusts and pathology networks on 25 May 2020, asking them to offer antibody testing at short notice and ramp up capacity to thousands of samples a day.
“We have three concerns about the request. Firstly, there is no specific clinical indication for the test on an individual basis. Secondly, the performance of these assays has not yet been assessed to the standard typically required of a novel test. And thirdly, the resource implications are not considered.”
They also expressed doubt around the “unproved performance” of the tests, adding: “The assay is being rolled out at an unprecedented pace and scale without adequate assessment, potentially compromising public trust in pathology services in the future.”
The letter adds: “NHS England requires the result to be available in 24 hours. Given that routine testing of patients is neither clinically urgent nor meets a clear public health need, this push to introduce a non-evidence based test for uncertain gains risks inefficient use of scarce resources.”
The experts also warned that a positive or negative test result would not alter how a patient is managed either way and added that a positive result “does not indicate immunity”.
Jon Deeks, professor of biostatistics at the University of Birmingham and The BMJ’s chief statistician said “we don’t have much data [on the tests] and we can’t trust any of it.”
The government website states: “While the results of an antibody test will not allow people to make any changes to their behaviour, such as easing social distancing measures, there’s clear value in knowing whether NHS and care workers and hospital patients and care home residents have had the virus, and in collecting data on the test results.”
A spokesman for Roche Diagnostics UK told The BMJ: “We are rolling out antibody tests to the NHS as part of the crucial next step in understanding the spread of this virus, and providing greater confidence and reassurance as we move into the next phase of our response to this pandemic.”
A Public Health England spokesman said: “Our evaluations have been completed in record time using the samples and tests that were available to us. We are confident that the volume of samples and methodology was of a high standard.”
In a statement to The BMJ, the Department of Health and Social Care said: “We do not currently know how long an antibody response to the virus lasts, nor whether having antibodies means a person cannot transmit it to others.”
But the spokesman reiterated that antibody testing “will play an increasingly important role as we move into the next phase of our response to this pandemic”.