Rapid-Response Modelling of the COVID-19 Pandemic
Providing insights to influence pandemic policy
The COVID-19 pandemic in 2020 presented a colossal challenge to both governments worldwide and to epidemiologists. In response to the crisis, mathematical modellers from Warwick’s Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research (SBIDER) developed an age-structured, regional scale compartmental model to inform policymakers on disease transmission. This so-called “Warwick model” has been used to feed into estimates of the reproduction number for the Scientific Advisory Group for Emergencies (SAGE), and to formulate specific advice and interventions on issues such as school closures, social bubbles, circuit-breakers and vaccine prioritisation.
Research funded by: MRC, NIHR
At the start of any new infectious disease outbreak there is uncertainty around how it is transmitted, how rapidly it will spread, and which interventions could be effective. Additionally, a lack of available data can pose a problem, as can accounting for regional differences. Producing an effective model despite these challenges is vital, as a better understanding of these unknowns helps to inform government policymakers.
Compartmental models in epidemiology separate a population into different groups, such as people who are susceptible to a disease and people who are infectious, and then they follow exchanges between these groups over time. These models are used to predict important values, such as the reproduction or R number. The key advantage of the Warwick model is in the number of parameters feeding into, and resulting out of, the model itself. To produce COVID-19 estimates which are valuable to policymakers, the Warwick model balanced various factors, including:
Age-dependent susceptibility to the virus
Real-time calibration against hospitalisations and deaths, together with the results of testing
Symptomatic and asymptomatic transmission
Regional resolution, accounting for regional differences in control measures and social mixing
Throughout 2020, epidemiologists Keeling, Dyson, Hill and Tildesley at the University of Warwick maintained membership to advisory bodies responsible for providing scientific input into government policy, including the Scientific Pandemic Influenza Group on Modelling (SPI-M) and the Joint Committee on Vaccination and Immunisation (JCVI). Through SPI-M the Warwick model, alongside models from seven other universities, was used to estimate the R number. These estimates were critical in the timing and sequencing of relaxation of restrictions following the first lockdown. A report from Warwick, presented to SAGE, highlighted that social bubbles were relatively safe compared to other relaxation measures. In June of 2020, the Prime Minister announced support bubbles for single adult households, allowing them to meet with one other household for the first time. For vaccination, age prioritisation set out by the JCVI cited Warwick’s research as its scientific basis. This advice was subsequently reflected in the COVID-19 vaccination programme. Overall Warwick provided 57 reports to SPI-M in 2020, with 19 also presented to SAGE. The University continues to contribute to discussions on pandemic policymaking to this day through SBIDER and the Institute for Global Pandemic Planning.