COVID-19: hello social distancing

March 17, 2020 Jon Otter (@jonotter) COVID-19coronavirus, epidemic, modeling, pandemic, social distancing

The UK government yesterday announced a far-reaching package of social distancing measures to suppress the spread of COVID-19. These are based on some Imperial College London modelling work, published here. The model predicts that the UK approach to mitigate the impact of the UK epidemic would indeed reduce the overall number of people affected and those who die, but would still leave hundreds of thousands dead in an overwhelmed healthcare system. In contrast, a more intensive suppression approach would be effective in reversing the epidemic trend and keep the number of new cases to a low level – in the short term, at least.

The model tested and compared the impact of two approaches in the UK and US:

Mitigation – an attempt to flatten the curve and reduce impact on healthcare systems; the aim is to reduce the reproduction number (the number of secondary cases of each case), but not to <1.
Suppression – an attempt to reverse epidemic growth by reducing the reproduction number to <1.

Left unchecked, the model predicts that COVID-19 would infect 81% of the UK population and cause more than 0.5m deaths by the summer of 2020. Mitigation was found to halve deaths and reduce the total number of cases by two thirds. However, this would still mean hundreds of thousands of deaths and a healthcare system (particularly intensive care) overutilised many times over.