Science

Coronavirus test results must come in 24 hours, says Sage scientist


A massive expansion of testing will still leave Britain struggling to keep Covid-19 infections under control unless the system can inform people they are positive within 24 hours, one of the government’s most senior scientific advisers has warned.

Ministers have insisted that they are on course to hit a target of 500,000 tests a day by the end of the month, with suggestions this weekend that capability of a million tests a day could be reached by Christmas.

However, Graham Medley, a member of the government’s Scientific Advisory Group for Emergencies (Sage) and chair of its subcommittee on modelling, said that returning test results “ideally within 24 hours” was as critical as capacity in a successful test-and-trace system. He said if necessary, capacity should be curbed in favour of speed.

His advice is at odds with testimony from Dido Harding, the Conservative peer who heads NHS Test and Trace. When demand for tests was surging last month, she said a “conscious decision” was made to extend the turnaround time.

There are still significant delays in the test-and-trace system, according to the latest figures. In the first week of October, 32.8% of tests conducted at regional test sites were returned within 24 hours. The figure was 24.4% for local walk-in sites and 41.9% for mobile testing sites. The number of home-testing kits received within 48 hours was 16%.

Medley told the Observer: “There’s been a huge advance in terms of the capacity for testing, but I think we’re still learning how to optimise the use of that testing. The length of time it takes to get the test result is critical for the contact-tracing. And so there has to be a potential compromise between the volume of testing done and the ability to return the result, ideally within 24 hours.

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Graham Medley says volume is only important if the test results can be produced promptly.



Graham Medley says volume is only important if the test results can be produced promptly. Photograph: BBC Newsnight

“Suppose you could treble the number of tests you did, but only at the expense of returning them in a longer period of time, then that’s not really going to work. The volume is important, but only if it can be done promptly. The people doing it need to consider that delay as being as important as the volume.”

Sir Paul Nurse, the Nobel laureate and director of the Francis Crick Institute in London, said using smaller labs alongside the big, privately run Lighthouse labs could speed things up. “Big labs have very long lines of communication,” he said. “For very good reasons, they find it difficult to get the sample into them and the information aggregated rapidly. I call [our small labs] lifeboat labs. It’s local, it’s small. It’s a different way of working. Government should think about supporting them, as well as their big labs. We could have repurposed 20 to 30 labs in a month. We may still be able to, but we’ve lost a bit of goodwill.”

The warning over the speed of test results comes amid mounting concerns over tracing efforts. Last week saw another record low for reaching the contacts of those who tested positive, with only 62.6% of close contacts reached in England. Almost 250,000 contacts of people who have tested positive in England have not been reached by tracers since the end of May, according to Labour’s analysis of test-and-trace data. The research, verified by the House of Commons library, found that in the last week for which data is available, almost 80,000 close contacts were not notified.

Local public health experts again demanded a rethink. Dr Jeanelle de Gruchy, president of the Association of Directors of Public Health, said: “As is clear from the latest performance figures, the national element still requires significant and urgent improvement. That means quick access to, and turnaround of, testing and at least 80% of contacts reached, as recommended by Sage in May.

“Locally, directors of public health have developed their own contact-tracing functions to supplement what is happening nationally. This approach has proved effective at reaching the areas and communities that the national system cannot. They are also managing, with PHE [Public Health England] colleagues, more complex contact tracing and outbreaks in settings like schools, care homes and businesses. More funding and resources are critical to keep doing this valuable work.”

A Department of Health spokesperson said: “NHS Test and Trace is breaking chains of transmission – over 900,000 people who may otherwise have unknowingly spread coronavirus have been contacted and told to isolate. The number of people who were reached and asked to provide information about their contacts, has increased from 74.9% to 76.8% this week.

“We’re continuing to drive forward local contact tracing as part of our commitment to being locally led, with more than 100 Local Tracing Partnerships now operating, and more to come.

“Since its launch, 84% of contacts have been reached and told to self-isolate where communication details were provided.”



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