The first figures for the controversial service showed that 5,407 of the 8,117 people whose details it received between May 28 and June 3 were subsequently contacted.
From these 5,407 people with Covid-19, a total of 31,794 close contacts were subsequently identified as being at potential risk of having also been infected. Of these, 26,985, or 85 per cent – were then reached and asked to self-isolate – the vast majority within 24 hours.
But the service was unable to reach 4,809 people, 15 per cent of the total “at risk” group, figures from the Department of Health reveal.
Test and trace was launched across England on May 28. It is meant to form a “central part” of the Government’s strategy of lifting the lockdown by containing and controlling the virus and limiting its spread.
It should ensure that anyone with symptoms will be tested and their close contacts traced. Anyone found to be in close contact with someone who tests positive is required to isolate for 14 days, even if they have no symptoms, to avoid unknowingly spreading the virus.
The first figures came as London’s resilience chief Fiona Twycross said the NHS tracker app would not be ready until “Autumn”. She told the London Assembly that while the app might work on the Isle of Wight, where it has been downloaded by more than 50,000 people, it was feared there could be problems in dense cities, particularly in tower blocks.
People the service was unable to reach include those whose “contact details were unavailable or incorrect” or where there has been no response to text, email and call reminders.
This number also includes cases when people who tested positive “have not provided information about contacts”, the Department of Health report said.
It added: “The service has been unable to reach some contacts. This could be where contact details were unavailable or incorrect, or where there has been no response to text, email and call reminders. Further, there are some contacts who were reached but have not agreed to self-isolate.”
The system advises people who have been in close contact with people subsequently found to have tested positive to go into 14-day quarantine at home – regardless of whether they have symptoms.
This has sparked concerns about the impact on the NHS and care homes if thousands of staff without symptoms are required to isolate.
People who test positive are contacted by NHS Test and Trace and required to share information about their recent interactions with people with whom they have been in direct contact, or within 2 metres for more than 15 minutes.
If people in isolation develop symptoms, they can book a test at nhs.uk/coronavirus or by calling 119. If they test positive, they must continue to stay at home for 7 days or until their symptoms have passed. If they test negative, they must complete the 14-day isolation period.
Members of the traced person’s household will not have to stay at home unless the person identified becomes symptomatic, at which point they must also self-isolate for 14 days to avoid unknowingly spreading the virus.
The Test and Trace service uses 25,000 contact tracing staff, online services and local public health experts to identify any close recent contacts.
The service “will have the capacity to trace the contacts of 10,000 people who test positive for coronavirus per day” and can be scaled up if needed.
Last month the Department of Health said the NHS Covid-19 App, trialled in the Isle of Wight, is due to be rolled out “in the coming weeks”.
Professor John Newton, national co-ordinator of Test and Trace, said they were “quite impressive figures” and showed “high levels” of public compliance with contact tracers. “In general, we are very pleased to see these data,” he said.
Baroness Dido Harding, executive chair of NHS Test and Trace, said: “Tens of thousands of people have engaged with NHS Test and Trace in its first week, either by taking a test if they have got symptoms or sharing their contacts if they test positive.
“We clearly have more to do to make sure we reach everyone, and a lot more to do to improve the speed of the end to end service, but we have really significant testing capacity.”
She thanked people who had co-operated, saying: “Thank you to all those people who are not probably feeling ill at this stage who have decided to do what is right to protect themselves, their family and their communities. It’s really heartening to see everybody join together to do that.”
Figures from the Downing Street press conferences show there were more 13,000 infections in the first week of Test and Trace – raising questions about why the new service may have only been told about 8,117 cases.
This discrepancy was put down to “double counting” – as some people may have had more than one test.
Baroness Harding said some people had declined to share details of their friends and contacts, telling contact-tracers: “I have already told my mates I tested positive, so I don’t need you to.”