Clinical academics and physicians have expressed concerns over the rollout of COVID-19 antibody testing in England.
Writing in The BMJ, they argue that there is no valid clinical reason for large scale testing and that test performance has not yet been adequately assessed.
The Prime Minister, Boris Johnson, has described antibody testing as "game-changing", and last month the Government said it had bought 10 million test kits from Abbott and Roche.
In May, Matt Hancock, the Secretary of State for Health and Social Care, called reliable SARS-CoV-2 antibody testing on a large scale "an important milestone" in developing so-called 'immunity passports'.
However, the 14 experts write: "The concept of 'immune passports', allowing healthcare workers or others to work, has not been established. Those with a positive antibody test should still consider themselves at risk and follow infection control policies designed to prevent nosocomial spread and risk of infection. There is, therefore, no benefit to healthcare organisations or to others in knowing the status of employees at present."
The letter also expresses worries that ramping up antibody testing could stretch NHS resources.
The group say they are also concerned that the tests are being rolled out with no data on performance in high risk groups, including the elderly, those from black and minority ethnic groups, and immunocompromised people.
They write that large scale SARS-CoV-2 IgG antibody testing should be limited to research purposes, including public health surveillance, "through carefully designed studies with clear objectives".
'Lack of Data'
An investigation, 'Why covid-19 antibody tests are not the game changer the UK government claims', also published in The BMJ, also expresses doubts about the usefulness of the current programme of antibody testing.
It quotes Jon Deeks, professor of biostatistics at the University of Birmingham, and The BMJ's chief statistician, who led the Cochrane review into COVID-19 testing, who said the analysis shows that "we don’t have much data [on the tests] and we can’t trust any of it".
The BMJ said it had seen an advance copy of the Cochrane review which it said concluded that "the data supporting existing antibody tests are so vague that it's impossible to know how accurate the tests are, especially for people with mild or no symptoms or after symptoms have gone".
Eleanor Riley, professor of immunology and infectious disease at the University of Edinburgh, said random testing of individuals without any research purpose did not make sense. "Because the test is not 100% accurate, whatever the result, the information is essentially meaningless to the individual."
She told the Science Media Centre: "There is currently no validated 'immunity certificate' that anyone can rely on to inform their risk or their behaviours.
"I would like to see the antibody tests that are available reserved for large scale epidemiological studies that can inform the risk for us all and help us to plan for the future rather than see them wasted on testing individuals for no obvious benefit."
Dr Tom Wingfield, senior clinical lecturer and honorary consultant physician at the Liverpool School of Tropical Medicine, said he shared the concerns raised in the letter.
He said that "although antibody testing could play an important role in understanding and controlling the Covid-19 pandemic, we don’t yet have sufficient evidence on accuracy and interpretation of antibody tests.
"Before such evidence is generated, it is difficult to see how a safe, comprehensive, and scientifically sound strategy for scale-up of antibody testing in the UK could be devised."