The government’s target of carrying out 100,000 Covid-19 tests each day by the end of the month has come under criticism from senior scientists, who say it will be impossible to reach.
Experts told the Guardian that a “macho” focus on headline-grabbing figures had been pursued at the expense of rigorous science.
The Cabinet Office minister, Michael Gove, said on Sunday that the government was confident that the goal of 100,000 tests daily by the end of April would be met.
However, scepticism is building. On Saturday, only 21,626 tests were carried out.
Paul Hunter, a professor of medicine at the University of East Anglia, said he viewed the target as impossible. “I cannot see that being achieved,” he said. “It was always designed to be a headline grabber rather than anything else.”
Others said a relentless focus on the number of tests performed each day had led to basic data reporting standards falling by the wayside. Prof Sheila Bird, formerly of the Medical Research Council’s biostatistics unit at the University of Cambridge, said: “The level of incompetence in reporting these tests is outrageous.”
Gove acknowledged on Sunday that the target referred to tests carried out. In the past fortnight the government has placed a growing emphasis on “testing capacity”. It said that although fewer than 22,000 tests were performed on Saturday, labs now had the capacity to carry out 38,000 tests daily, and this had not been fully taken up by hospitals.
Scientists said the distinction was misleading as the logistics of having enough doctors and nurses on the ground to perform swab tests and send off samples continued to be a challenge. “Having the capacity is just the first step,” said Bill Hanage, a British epidemiologist based at Harvard.
Bird said the failure to give breakdowns of how many tests were being carried out on patients in hospital, critical workers and family members of critical workers made it impossible to extract prevalence rates of infection in these different groups and other crucial information that would allow scientists to more accurately assess the status of the outbreak in the UK.
“This macho thing about the number of tests done each day is leading to a reporting standard that makes the data almost uninterpretable,” she said.
Ideally, she said, tests would be reported separately for these different groups and would take into account the fact that hospitalised patients typically have a sequence of three tests over several weeks – an initial positive test followed by two negative tests (the second negative for assurance that the recovering patient is no longer infectious and can be transferred home or to a general ward).
“Reporting the number of tests performed each day is a political requirement, not a scientific requirement,” she added.
Hanage said that even if the 100,000 target were met, this figure was not a relevant measure of the adequacy of the UK’s testing operation. “Aiming for a large number that sounds good is not the way you should be doing this,” he said.
That around a third of those tested in the UK this week had positive results suggests that, while useful for guiding medical treatment, current testing is far below the levels that would be needed for population surveillance.
“The data I’ve been seeing suggests there’s not anywhere near enough testing,” Hanage said. “The way you should be doing it is to build the capacity and ability to run large numbers of tests – enough that only 10% are coming back positive.”
The World Health Organization has repeatedly urged governments to pursue testing and tracing, and some countries, including Singapore and South Korea, have successfully used this approach to contain their outbreaks, while Germany has also continued to carry out contact tracing.
The UK abandoned population testing and contact tracing in early March, when case numbers began to rise steeply, but the health secretary, Matt Hancock, said on Friday that contact tracing would be reintroduced, including through a proposed NHS smartphone app.
Experts say the ability to rely on this approach to safely exit the lockdown will depend critically on widespread population testing beyond the level needed for diagnosing patients in hospital.