Boris Johnson and his chief scientific adviser have admitted to failings in England’s £12bn test-and-trace system as contact-tracing fell to a new low and waiting times for test results soared to almost double the target. Under pressure to explain new figures showing less than 60% of close contacts being reached, while test turnaround times rose to nearly 48 hours, the prime minister said: “I share people’s frustrations and I understand totally why we do need to see faster turnaround times and we need to improve it.” The system, designed to contain outbreaks by ensuring anyone exposed to the virus self-isolates, was helping “a bit”, Johnson added. “The thing depends on people self-isolating and breaking the transmission. It is helping a bit already to break the transmission. About 1m contacts have been reached. But there is more that it can do if everybody complies once they are contacted by NHS Test and Trace.” Alongside him at a Downing Street press conference, Sir Patrick Vallance said problems with test and trace were in part inevitable as coronavirus cases rose in the second wave – but also a result of the system’s operation. They were “diminishing its effectiveness”, he said. Another expert said test and trace was “struggling to make any difference to the pandemic”. In the week ending 14 October, 59.6% of close contacts were reached, down from the previous week’s figure of 62.6%, which was the lowest since the test-and-trace operation was launched at the end of May. Sage said in May that at least 80% of contacts must be reached for the system, described as “world-beating” by the government, to be effective. Documents published last week show Sage considers its success to be “marginal”. In fact the true proportion of contacts of Covid patients reached is lower still: the latest report reveals 101,494 people tested positive but only 96,521 were transferred to the contact-tracing system, of whom just over 80% were reached and asked to provide information about their contacts. That means, overall, only 46% of close contacts were reached. The latest performance statistics, published on Thursday, also showed Boris Johnson is further from delivering on his pledge that the results of all in-person tests will be returned within 24 hours. The median time taken to receive a test result at regional sites rose to 45 hours, from 28 the previous week. Local test site result times increased to 47 hours from 29, and mobile test units rose to 41 hours from 26. Vallance told a Downing Street press conference on Thursday: “It’s really important to concentrate on numbers of contacts [and] isolation as quickly as you can and getting things back as quickly as you can, ideally to get the whole process done within 48 hours. And it’s very clear there’s room for improvement on all of that … and therefore that will be diminishing the effectiveness of this.” James Naismith, a professor of structural biology at the University of Oxford, said of the figures: “[They] show a system struggling to make any difference to the epidemic … The current system indicates that around two-thirds of infected people do not have contacts traced at all. Of the contacts provided, around 60% of the contacts are reached. “Of those that are reached, over 70% of them are in the same house as the positive case, so were unlikely to have needed the tracing system. Only half of all contacts that are actually traced are reached within 24 hours. “These statistics are a stark demonstration of what Sage concluded and we can see with our eyes: the system has given a bird’s eye view of the pandemic and done very little to halt it.” He suggested the test-and-trace system may be beyond repair. For cases handled by local health protection teams, 94.8% of contacts were reached and asked to self-isolate, but for those handled either online or by call centres the figure was 57.6%. The disappointing performance figures were accompanied by an increase in the proportion of people testing positive to 7.1%, although that could possibly be a result of more targeted testing. The positivity rate was 6.3% in the previous week and 0.9% in the week ending 26 August. The World Health Organization has recommended it should remain below 5% for at least two weeks before governments consider relaxing restrictions. Saffron Cordery, the deputy chief executive of NHS Providers, said the system was “falling short”, adding: “Most worrying of all is the failure to reach more than 100,000 close contacts this week. All this at a time when infections are rising and we’re heading towards winter, with the prospect of added seasonal pressures.” Just 7.4% of results from all test sites were received within 24 hours, compared with 14.8% in the previous week. For in-person tests – local test sites, mobile testing units and regional test sites – 15.1% were received within 24 hours, down from 32.8% the previous week and 94.3% at the end of June. For satellite test centres – private labs helping to increase testing capacity for hospitals and care homes – 22.3% of results were received within 48 hours, slightly up on the 21.1% in the week ending 7 October. Kevin McConway, emeritus professor of applied statistics at the Open University, said: “Increases in times to carry out the testing and the tracing inevitably mean that more people who are potentially infectious and should already be self-isolating are walking around, potentially infecting people, probably without even knowing that they are at higher risk of being infectious. This really isn’t good enough.” Dido Harding, the interim executive chair of the National Institute for Health Protection, said: “Reducing turnaround times is our absolute priority to make sure we are reaching people as soon as possible. We always need to balance ensuring as many people as possible can get a test alongside ensuring test results are delivered as quickly as possible, and as capacity continues to grow at pace, we expect to see improvements.”