The head of the UK’s test and trace programme has defended paying hundreds of private consultants an average of £1,000 a day, as she set out plans to spend billions on rapid testing technologies in the coming months.

The questions over spending on consultants comes after widespread criticism of the programme, which in October was reaching only 60 per cent of the contacts of people who tested positive for Covid-19.

Dido Harding, head of the programme, said there had been considerable improvement in recent weeks, with contact tracers now reaching over 80 per cent of people who test positive and 90 per cent of their close contacts. She added that testing capacity was now at over 800,000 per day.

Speaking at the Commons public accounts committee on Monday, Lady Harding said: “As measured, we are having a material impact in the fight against Covid.” She was responding to comments late last year by the government’s Scientific Advisory Group for Emergencies (SAGE), that the programme had only a “marginal” impact on transmission of the virus.

Lady Harding told MPs that the test and trace programme had reduced the R number — the average number of new cases generated by an infected individual, which governments use to gage how fast the virus is spreading — by between 0.3 and 0.6 in October.

She added that by March, the programme would be helping to reduce R by between 0.5 and 0.8.

Asked whether she was embarrassed about the amount being spent on private consultancies, Lady Harding said: “It’s appropriate to build a service in extreme circumstances, using consultants for some of those roles. They’ve done some very important work.”

There are currently 900 consultants from Deloitte working on the government’s test and trace programme, earning an average day rate of £1,000 — roughly £22,000 a month — David Williams, second permanent secretary at The Department of Health and Social Care, told the MPs.

Mr Williams confirmed that a total of £8.3bn of the £22bn annual budget for the programme had so far been spent, with a further £13bn forecast to be injected in the next few months.

“Testing continues to be the principal driver of cost,” he said, adding that a greater proportion of funds would be used to pay for so-called “lateral flow tests” in the coming months. The tests, which give results in under 30 minutes, have been widely criticised in recent weeks because of their failure to detect active infections, which make it dangerous to rely on negative results.

A total of 623m so-called lateral flow tests have already been bought, with a tender out to procure a further 200m tests from mid-February, Mr Williams said.

Lady Harding said that using the devices to test every person in specific regions of the country was “definitely one of the suites of options” they were considering for the tests in their arsenal.