COVID-19: Imperial College Researchers’ Model Likely Influenced Public Health Measures

disease. Such epidemics are predicted to peak over a three to four-month period during the spring/summer.

In the second scenario, more intensive interventions could interrupt transmission and reduce case numbers to low levels. However, once these interventions are relaxed, case numbers are predicted to rise. This gives rise to lower case numbers, but the risk of a later epidemic in the winter months unless the interventions can be sustained.

Slowing and suppressing the outbreak
The report details that for the first scenario (slowing the spread), the optimal policy would combine home isolation of cases, home quarantine and social distancing of those over 70 years. This could reduce the peak healthcare demand by two-thirds and reduce deaths by half. However, the resulting epidemic would still likely result in an estimated 250,000 deaths and therefore overwhelm the health system (most notably intensive care units). 

In the second scenario (suppressing the outbreak), the researchers show this is likely to require a combination of social distancing of the entire population, home isolation of cases and household quarantine of their family members (and possible school and university closure). The researchers explain that by closely monitoring disease trends it may be possible for these measures to be relaxed temporarily as things progress, but they will need to be rapidly re-introduced if/when case numbers rise. They add that the situation in China and South Korea in the coming weeks will help to inform this strategy further.

Professor Azra Ghani, Chair in Infectious Disease Epidemiology from the MRC Centre for Global Infectious Disease Analysis, said: “The current situation with the COVID-19 pandemic is evolving rapidly; governments and societies therefore need to be flexible in responding the challenges it poses. Our results indicate that widescale social distancing measures, that are likely to have a major impact on our day-to-day lives, are now necessary to reduce further spread and prevent our health system being overwhelmed. Close monitoring will be required in the coming weeks and months to ensure that we minimise the health impact of this disease.”

Professor Christl Donnelly, Professor of Statistical Epidemiology within J-IDEA, said: “The challenges we collectively face are daunting.  However, our work indicates if a combination of measures are implemented, then transmission can be substantially reduced.  These measures will be disruptive but uncertainties will reduce over time, and while we await effective vaccines and drugs, these public health measures can reduce demands on our healthcare systems.”

Professor Steven Riley, Professor of Infectious Disease Dynamics within J-IDEA, said: “We have to accept that COVID-19 is a severe infection and it is currently able to spread in countries such as the US and the UK. In this report, we show that the most stringent traditional interventions are required in the short term to halt its spread. Once they are in place, it becomes a common priority for us all to find the best possible ways to improve on those interventions” 

Dr. Sabine L. Van Elsland is External Relationships & Communications Manager at Imperial College London. Ryan O’Hare is Research Media Officer (Medicine) at Imperial College London. This article is adapted from a press release from the MRC Centre for Global Infectious Disease Analysis, and is published courtesy of Imperial College London.