An academic has warned that the £22 billion NHS test-and-trace system risks being overwhelmed by surging infections after the planned wholesale lifting of restrictions on 19 July.

Jon Deeks, a professor of biostatistics at the University of Birmingham, has said that at least 660,000 gold-standard PCR tests are likely to be needed each day to discover 100,000 daily infections this summer – the number forewarned by Health Secretary Sajid Javid after the government announced plans to drop restrictions from 19 July.

Such a level of testing is almost three times the current rate in the UK, more than double the highest volume achieved at any point during the pandemic, and at the peak of the system’s theoretical laboratory capacity calculated this spring by the National Audit Office.

This could mean that rationing may be required in the areas where contact tracing is carried out, focusing on poorer locations on the basis that residents are more likely to live in overcrowded conditions and have face-to-face jobs.

NHS Test and Trace data shows that positive tests in England were up 71 per cent in the last week of June – the highest number since early February. Turnaround times have also increased, with the proportion of in-person test results returned in 24 hours down to 77 per cent from 84 per cent the previous week.

PCR testing capacity has been reduced by more than 100,000 tests per day since the end of March, according to the NAO, but it has increased 45 per cent in the last four weeks.

Deeks told the Guardian: “If we get to 100,000 cases a day, the capacity of our testing system is going to be breached, particularly when we build in the recommendation for testing contacts. Plus some of the labs are being shut down, such as the turnkey lab here at the University of Birmingham.”