UK modelling study finds case isolation and contact tracing vital to COVID-19 epidemic control


18-06-2020
  Coronavirus (COVID-19) Sheffield, UK  Credit: Tim Dennell

In the absence of a vaccine or highly effective treatments for COVID-19, combining isolation and intensive contact tracing with physical distancing measures—such as limits on daily social or workplace contacts—might be the most effective and efficient way to achieve and maintain epidemic control, according to new modelling research.

Using social-contact data on more than 40,000 individuals from the BBC Pandemic database to simulate SARS-CoV-2 transmission in different settings and under different combinations of control measures, the researchers estimate that a high incidence of COVID-19 would require a considerable number of individuals to be quarantined to control infection. For example, a scenario in which 5,000 new symptomatic cases were diagnosed each day would likely require 150,000–200,000 contacts to be quarantined every day if no physical distancing was in place.

The study -  published in The Lancet Infectious Diseases journal - is the first time researchers have used social contact data to quantify the potential impact of control measures on reducing individual-level transmission of SARS-CoV-2 in specific settings. They aimed to identify not only what would theoretically control transmission, but what the practical implications of these measures would be in terms of numbers quarantined.

However, the authors note that the model is based on a series of assumptions about the effectiveness of testing, tracing, isolation, and quarantine—for example about the amount of time it takes to isolate cases with symptoms (average 2.6 days) and the likelihood that their contacts adhere to quarantine (90%)—which, although plausible, are optimistic.

“Our findings reinforce the growing body of evidence which suggests that we can’t rely on one single public health measure to achieve epidemic control,” said Dr Adam Kucharski from the London School of Hygiene & Tropical Medicine. “Successful strategies will likely include intensive testing and contact tracing supplemented with moderate forms of physical distancing, such as limiting the size of social gatherings and remote working, which can both reduce transmission and the number of contacts that need to be traced.”

He adds: “The huge scale of testing and contact tracing that is needed to reduce COVID-19 from spreading is resource intensive, and new app-based tracing, if adopted widely alongside traditional contact tracing, could enhance the effectiveness of identifying contacts, particularly those that would otherwise be missed.”

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Image: Coronavirus (COVID-19) Sheffield, UK

Credit: Tim Dennell

Reproduced courtesy of the University of Cambridge

 

The University of Cambridge is acknowledged as one of the world's leading higher education and research institutions. The University was instrumental in the formation of the Cambridge Network and its Vice- Chancellor, Professor Stephen Toope, is also the President of the Cambridge Network.

University of Cambridge (cam.ac.uk)