The UK’s first mass Covid testing trial in Liverpool risks being “an expensive mess that does more harm than good”, health experts said as it got under way on Friday. Six new testing centres opened their doors to Liverpudlians at midday on Friday as part of the government’s Operation Moonshot drive to eventually test up to 10 million people a day. Huge queues had formed before some of the centres had opened, indicating significant early demand. The Liverpool football club manager, Jurgen Klopp, joined council bosses in urging the city’s 500,000-strong population to volunteer for a test, but it remains to be seen how many will come forward. Joe Anderson, the Liverpool mayor, said: “This is an incredible opportunity to turbo-charge our efforts to reduce coronavirus in the city.” However, five public health experts, including Allyson Pollock, a professor of public health at Newcastle University, raised significant doubts about the trial in a letter to Liverpool MPs. They said the plans to test asymptomatic people in Liverpool went against advice from the Scientific Advisory Group for Emergencies (Sage) to prioritise the testing of people displaying symptoms, and “searching for symptomless yet infectious people is like searching for needles that appear transiently in haystacks”. “The potential for harmful diversion of resources and public money is vast. Also of concern are the potential vested interests of commercial companies supplying new and as yet inadequately evaluated tests.” Angela Raffle, a public health consultant in Bristol, said she had looked carefully at the Liverpool proposals and concluded they were not fit for purpose. “Experience with screening tells us that if you embark on a screening programme without having carefully evaluated it first, without a proper quality-assured pathway, without certainty of test performance in field settings, without full information for participants, and without the means to ensure that the intervention needed for those with positive results does indeed take place, the result is an expensive mess that does more harm than good,” she said. The pilot began amid confusion about whether NHS staff with no symptoms would be offered a saliva test, as originally intended as part of the trial. The OptiGene Lamp tests, for which the government has paid £323m, are separate to the nasal swab tests used by the public, and there are questions about their accuracy. A trial in Greater Manchester found they missed half of infections, but the government said they had performed better in other pilots, without releasing the data. Matt Ashton, Liverpool’s director of public health, said on Friday: “There are lots of different testing technologies coming onboard. The saliva one is the one that’s commonly referred to as Lamp testing, but Lamp testing is not part of the Liverpool pilot.” Similarly, a spokesman for Liverpool university hospitals NHS foundation trust said it was not using the OptiGene Lamp tests on NHS staff or patients. This appeared to contradict the Department of Health and Social Care, which had said the OptiGene Lamp test would be used as part of the trial by NHS staff. Significantly, people who do not have coronavirus symptoms are being urged to get tested. It is estimated that about one in four people who get the disease will never show symptoms, according to Bertie Squire, a professor of clinical tropical medicine at Liverpool School of Tropical Medicine.