LAST month, UK prime minister Boris Johnson said England would have a 鈥渨orld-beating鈥� contact-tracing system in June. But as non-essential shops began reopening in England, the past week has seen two major blows to contact-tracing efforts there.
First, the UK government ditched an overdue National 午夜福利1000集合 Service app designed to automatically detect possible instances of virus transmission between people, after a trial on the Isle of Wight found its use of Bluetooth failed to detect many iPhones running the app. The app was originally due to be rolled out across the UK in May.
The UK government will now pivot instead to build a new app relying on software that will be baked into Google and Apple鈥檚 mobile operating systems, it was announced on 18 June 鈥� an approach being pursued by many other countries. The app is unlikely to launch until winter, UK ministers indicated.
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Scotland and Northern Ireland are pursuing their own apps. In the current absence of such apps, the UK鈥檚 tens of thousands of human contact tracers have been attempting to break the virus鈥檚 chain of transmission. However, new figures show that England鈥檚 Test and Trace scheme, the biggest of the UK鈥檚 four nations, is still failing to contact around a quarter of people testing positive.
During the scheme鈥檚 second week, from 4 to 10 June, only 73 per cent of the 5949 people who tested positive were successfully contacted, a similar proportion to the launch week. Initial contact is key to establishing the person鈥檚 recent close contacts. Similar contact-tracing operations in Wales, Scotland and Northern Ireland aren鈥檛 yet publishing comparable statistics.
England鈥檚 scheme hasn鈥檛 yet released data on its speed of operation, from the point at which someone orders a test to when their close contacts are told to self-isolate. A quick turnaround is vital to contain the virus鈥檚 spread.
One contact tracer for the scheme told New Scientist that they were typically phoning people to tell them they had tested positive around three days after the person first developed symptoms and ordered a test.
Newly published minutes show that the UK government鈥檚 Scientific Advisory Group for Emergencies (SAGE) said a month ago that the contact-tracing operation 鈥渃ould very rapidly become overwhelmed鈥� if there were still high numbers of new covid-19 infections. At the time, there were around 10,000 new cases across the UK a day. In the past week, the UK government has been reporting around 1000 to 1300 confirmed cases a day.
鈥淥nly 73 per cent of people who tested positive in England were successfully contacted鈥�
The reproduction number 鈥� the average number of other people one infected person passes the virus on to 鈥� for the UK is at 0.7 to 0.9, while its infection growth rate appears to be at -2 to -4 per cent. Both these estimates suggest the outbreak is slowly declining. But there have been signs of isolated local outbreaks, such as at a meat plant in Anglesey, Wales, raising the prospect of a local lockdown by authorities.
Nevertheless, most indicators of the virus鈥檚 prevalence are showing a decline. Figures last week from an ongoing Office for National Statistics study suggest that an estimated average of 33,000 people, excluding those in care homes and hospitals, in England had covid-19 in the first two weeks of June, down from 149,000 in the first two weeks of May.
On Tuesday, Johnson announced that the 2-metre social distancing rule would be reduced to 1 metre in England from 4 July, in situations where other safety measures are in place. Without such measures, evidence considered by SAGE suggests that the shorter distance carries between two and 10 times the risk of transmission.
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