The US Food and Drug Agency (FDA) has raised significant concerns about the rapid Covid test on which the UK government has based its multibillion-pound mass testing programme. In a scathing review, the US health agency suggested the performance of the test had not been established, presenting a risk to health, and that the tests should be thrown in the bin or returned to the California-based manufacturer Innova. In the UK, these lateral flow Innova tests form the cornerstone of Operation Moonshot, the mass-testing scheme championed by the prime minister’s former chief adviser Dominic Cummings. The idea was that the ability to deliver results within 30 minutes – without the need for processing in a laboratory – provided a cheap, pragmatic and efficient way to identify people who had caught the virus but not fallen ill. But critics have raised concerns about accuracy. Given the tests have been offered free to millions in England, for use at home or at test centres, workplaces and schools, with the aim of detecting more cases, breaking chains of transmission and saving lives since April, the FDA announcement is particularly alarming. The US agency has not authorised the use of the Innova test in the US, although the manufacturer has submitted a request for authorisation. But when the FDA discovered the Innova test was being distributed for US use regardless, it conducted an inspection of Innova’s medical device operations between March and April 2021. In its report, the agency accused the company of “false or misleading” estimates of the clinical performance of certain configurations of the test, saying the estimates did not accurately reflect the performance of the diagnostic devices during clinical studies. The FDA also highlighted that the clinical study data submitted by Innova as part of its request for US authorisation was identical to data previously provided by other manufacturers in separate requests. In the UK, criticism of the Innova test has been fierce. The tests are not as effective as the gold-standard PCR tests, which can take days to produce results. The accuracy of the Innova tests also falls dramatically when administered by self-trained, non-healthcare workers versus lab scientists. But perhaps the biggest concern is that the tests only tend to pick up cases when the person has high levels of the virus. Typically, when a person is first infected they harbour low levels of virus. The UK government’s first contract with Innova was agreed on 17 September, before the evaluation of its tests had been completed. In December, the Medicines and Healthcare products Regulatory Agency (MHRA) – which is an executive agency sponsored by the Department of Health and Social Care – accepted the DHSC’s request to issue special authorisation of the Innova test. In early April, the UK government announced plans for the use of universal Covid-19 tests as a means to ease England out of lockdown. By the end of the month, the MHRA expressed concerns that the people who tested negative would be given false reassurance by their result and would let down their guard if they believed they were Covid-free – suggesting the government’s universal testing plan was “a stretch” of the authorised use of rapid tests. The MHRA’s special authorisation of the Innova test – which is repackaged and deployed by the NHS – is due for another review by 22 June. Ministers were urged to “urgently explain whether they are taking any action and asking UK regulators to look again at these tests in light of these findings” by Labour’s shadow health secretary Jonathan Ashworth. “We are aware of the FDA communication,” the MHRA director of devices Graeme Tunbridge said. “The MHRA are reviewing all available information and are working closely with NHS Test and Trace to ensure that a full risk assessment is undertaken, as is our normal process, to understand any implications for products being used in the UK. Patient safety is our main priority and we will issue safety information as and when necessary.” An Innova spokesperson said: “The Innova rapid antigen test has been widely used, studied, tested, scrutinised and analysed with data supporting the efficacy of the test from the largest mass testing programme out of the UK. Innova is confident about the quality of its product.” A DHSC spokesperson said the Innova test had already gone through the UK’s rigorous Porton Down assessment process. A report published on the evaluation carried out at the Porton Down lab in November showed that the accuracy of the Innova test was on average 79% when the test was given by lab scientists, 73% when administered by health workers and 57.5% when people swabbed themselves. But data suggests that the test performs worse in the real world. Liverpool was the first city to pilot the test for mass testing of people without symptoms – about 125,000 residents took the tests between 6 November and 9 December. Of those, 897 people who did not know they had the virus tested positive. However, tests in the field missed 60% of infections in people who were self-swabbing. “We have a robust quality assurance process in place,” the DHSC spokesperson said. “We have confidence in lateral flow tests, which help us identify people without symptoms but who could pass the virus to others – helping break the chains of transmission.”