Just 8pc of people account for 60pc of Covid transmissions
A tiny fraction of people could be behind the vast majority of the UK’s coronavirus cases, a study from the Government’s former nudge unit suggests, raising doubts about the effectiveness of Britain’s approach to contact tracing.
Eight per cent of individuals accounted for over 60 per cent of transmission risk in a study conducted by the Behavioural Insights Team (BIT), now independent of the Government but founded by the Cabinet Office in 2010 to apply behavioural science to public policy.
The findings suggest that identifying the superspreaders who infected a person in the first place – as opposed to getting in touch with their contacts – could be a more effective approach to stopping the spread of coronavirus.
BIT asked over 3,700 Britons at the end of October how many people they had met outside of their household – including their support bubble – in the last seven days.
Most, 75 per cent, said they had been keeping to themselves, meeting no-one or only one to two people outside their household while taking safety precautions like being outdoors and wearing masks.
Such cautious behaviour accounted for just one per cent of the risk of spreading coronavirus, according to BIT’s analysis.
Instead the vast majority of transmission risk came from only eight per cent of respondents – deemed “potential superspreaders” by BIT. These people said they had met three or more people, typically indoors with no masks and without keeping distance.
BIT also found potential superspreaders had no specific demographic characteristics; they were not disproportionately male, young, or from any particular ethnic group.
The findings come as NHS Test and Trace continues to fail to notify at least 80 per cent of contacts, a level recommended by Scientific Advisory Group for Emergencies (SAGE) advisers. See below the Test and Trace promotional video.
Latest figures show that 313,771 people were identified as coming into close contact with someone who had tested positive for Covid-19 between November 5 and November 11.
For those where communication details were available, 77.9 per cent were reached and asked to self-isolate. Taking into account all contacts identified, 60.5 per cent were reached.
In October, Whitehall sources said preparations were being made to introduce so-called "backward tracing" to pinpoint "superspreader" events, but that they were waiting for infection rates to drop.
BIT suggested its findings may support the strategies of Asia-Pacific countries such as Singapore, Japan, and South Korea, which have used backward contact tracing or “cluster busting” strategies to help bring their own outbreaks under control.
“The rationale for backward tracing is that if roughly 70 per cent of cases do not pass the virus on to others, then the efforts spent chasing the recent contacts of that group would be of less benefit than tracking down people with many recent high-risk contacts,” said the BIT.