NHS Test and Trace is struggling in the hardest-hit areas of England

For a test and trace system to be effective, it has to scale up at the same rate as cases rise, otherwise it becomes increasingly redundant.

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NHS Test and Trace is struggling to keep up with cases in the majority of local authorities in England, a New Statesman analysis of government data has found. Around three-quarters of local authorities in the country saw more than 5 per cent of tests returning a positive case in the week ending 21 October.

A higher test positivity rate spells bad news for the test and trace system – as it is likely there is a greater number of infected people not being tested. In May, the World Health Organisation (WHO) recommended that the positivity rate remains below a rate of 5 per cent for at least two weeks before governments should consider reopening – though this referred to countries as a whole, rather than regions or cities.

Testing is struggling to keep up in the hardest-hit parts of the country

The figures show that testing is struggling to keep up with cases in the worst-hit parts of the country. Blackburn with Darwen – which saw the highest number of cases per 100,000 people in the week to 21 October (788) – saw 19 per cent of tests return positive, more than anywhere else in England.

Test and trace is struggling in areas with higher case rates
Test positivity rate and cases per 100,00 people, week ending 21 October

That was followed by Bolton (18 per cent), Rossendale (18 per cent) and Stockton (18 per cent), all of which are among the worst-hit areas for cases. Of the 20 upper-tier local authority areas with the highest positivity rate, 12 were in the north west – the region with the highest number of Covid-19 cases.

The map below shows the percentage positivity rate in the most recent week of data for English local authorities. Those in pale yellow are catching most of their cases using testing – and are under the WHO threshold of 5 per cent. In the dark blue areas, testing is falling behind the high case rates, and it is likely there are many more cases in the community than are being recorded.

Testing is failing to keep up with cases in the north west
Percentage of cases returning positive by local authority, week ending 21 October 

Failing to test people with Covid-19 is only part of the problem. Even once most of the positive cases are transferred into the tracing system, not everyone is reached and asked to provide details of their close contacts. This contact tracing is especially poor in the capital: of the 20 local authorities with the lowest contact rate, ten were London boroughs. In the latest week, Hammersmith and Fulham council was able to contact just two-thirds (67 per cent) of people entered into the tracing system.

Meanwhile across England, just 84 per cent of those successfully contacted were able to provide details of a close contact. Even then, there is no guarantee that their information will be followed up. Extremely high numbers of cases in the north west, with huge numbers being entered into the system, mean that teams are struggling to chase contacts. In the latest week, 49 per cent of close contacts identified in Bradford were reached by NHS Test and Trace.

[see also: Junior doctor survey reveals the areas of the NHS hit hardest by Covid-19]

That said, the failings in tracing aren’t limited to any one region. Just 54 per cent of close contacts were reached in Birmingham in the week to 21 October, and parts of the capital are also seeing low contact rates – 56 per cent in Redbridge and 53 per cent in Hackney and the City of London. Hovering or clicking on an area in the map above will show you the percentage of close contacts reached.

An effective test and trace system isn’t a silver bullet and won’t, on its own, stop the spread of Covid-19. But failing to implement a successful one means fighting the virus blind. The figures for the UK are a major concern – as is the fact they are worse in those areas with the highest number of cases. For a test and trace system to be effective, it has to scale up at the same rate as cases, otherwise it becomes increasingly irrelevant. 

One hope is that a new lockdown will reduce the case rates enough for the system to gain the upper hand. But the fear is it might already be too late.

Michael Goodier is a data journalist at New Statesman Media Group

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