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Covid-19: NHS Test and Trace releases first figures, with experts calling for improvements

BMJ 2020; 369 doi: (Published 15 June 2020) Cite this as: BMJ 2020;369:m2404

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  1. Elisabeth Mahase
  1. The BMJ

Three months after the UK stopped contact tracing, a new NHS Test and Trace service launched last week. Can teething problems be ironed out, and is it fit for purpose? Elisabeth Mahase finds out

The new NHS covid-19 contact tracing service for England identified and advised 26 985 contacts to self isolate in its first week, the first reported statistics show.1

Some 8117 people who tested positive for covid-19 had their case transferred into the Test and Trace service between the service’s launch on 28 May and 3 June. Of these, 5407 (67%) people were reached and asked to provide details of contacts. Just under 32 000 contacts were identified.

But this means that 33% of people who tested positive were not reached and therefore their contacts have not been traced.

Speaking at a press conference on 11 June, Dido Harding, who runs NHS Test and Trace, said, “Clearly there is more for us to do . . . It isn’t [perfect]. But we are encouraged by the way the public are responding and the figures we are publishing today.”

The system, overseen by Public Health England, works by physical contact tracers contacting people to tell them that they have been in close contact with someone who has tested positive for covid-19 and advising them to isolate for 14 days. The government has said it is the public’s “civic duty” to follow requests from contact tracers.

Incomplete data

Anne Johnson, professor of infectious disease epidemiology at University College London, said, “Given the speed of set up, they have got off to a good start,” adding that a “major benefit of the new system” was the wide availability of testing.

She said, “Early signs are that the contact system is acceptable to a high proportion of the population and a majority are reached within 24 hours of a positive result. But there is more work to be done on speeding the system and on data quality and completeness.”

Johnson, a member of the Data Evaluation and Learning for Viral Epidemics (DELVE) committee that produced a report on the test, trace, and isolate method for the Royal Society, also said that it would be good to get more data on the regional breakdown of cases and on the “substantial proportion of cases and contacts being identified as part of outbreaks by local public health teams.”

Sheila Bird, former programme leader of the MRC Biostatistics Unit at the University of Cambridge, agreed that though a “good start has been made” the data were incomplete.

“For some reason, time from referral to contacting of the index case has been documented for only 4216 (78%) of the 5407 index cases who were reached: for 3336 (79%) of these 4216 index cases, referral to contact time was within 24 hours. But time intervals are missing for 21% of index cases,” she said.

Bird also pointed out that although the government had said that 85% of contacts who were asked to self isolate were reached within 24 hours, this proportion related to only 5278 of the 26 985 contacts reached. She said this was “so low a percentage that the distribution of the reported times could be importantly different” from that for the total number of contacts.

The report said data were incomplete because of a high number of contacts being managed by local public health teams as part of outbreak investigations, meaning they could not be included in the figures.

Aside from the analysis within the report, the Independent Scientific Advisory Group for Emergencies (iSAGE) has also raised concerns over the difference between the number of new covid-19 cases picked up by the service and the number estimated by the Office of National Statistics.

The group said, “Only 5407 (67%) were reached and asked to provide details of recent contacts. ONS surveillance data, however, suggested that there were at least 23 000 new symptomatic cases during that time period, meaning that only about a quarter of symptomatic cases had been found by the Test and Trace system.” the group said.

David King, chair of iSAGE, said, “It is of course reasonable to expect that the first week of a new programme like this will have teething problems. However, these figures are alarming. What is of particular concern is that we are continuing to see the country coming out of lockdown before a fit for purpose—let alone world beating—test, track, and trace system is up and running.”

The warning came after iSAGE released a report arguing that the government’s test and trace system was “not fit for purpose” and in need of a radical overhaul. The group said the government should shift from a centralised to a locally led system coordinated by directors of public health.2

Testing contacts

Other experts have questioned why, unlike in other countries, contacts are not being tested in England unless they show symptoms.

Mark Harris, professor of virology at the University of Leeds, said, “What is both surprising and concerning is that the contacts identified are only being asked to self-isolate for two weeks. Why are they not being tested, as is undertaken in other countries? By testing contacts we will also be able to identify other infected individuals and broaden the scope of the contact tracing to the next tier of contacts. This will help in identifying potential foci of infection and possibly inform localised lockdown strategies.

“We have the capability to test these contacts. As we have heard in many government press conferences the facilities for large scale testing are now operational. It is clear, however, that some of these facilities are working well below capacity, due to a lack of samples. This disconnect needs to be addressed urgently.”

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