Disease modelling experts at The University of Western Australia have identified the optimal time in a COVID-19 outbreak to introduce an early and hard lockdown to “catch and contain” the growth rate and limit cases, hospitalisations and loss of life. 

Lead researcher Professor George Milne and his team carried out computer simulation “virtual world” COVID-19 modelling. This showed that to prevent healthcare facilities from being overwhelmed, the first sign of case numbers increasing exponentially should be used as the trigger to go straight into a hard Stage 4 lockdown, with schools closed and leaving home only for essential work and essential shopping.

The modelling showed that if Melbourne had reacted this early and this hard during its second wave last year – with an immediate hard Stage 4 lockdown when there was the first sign of cases doubling every seven to 10 days – there would have been at least a 60 per cent reduction in cases, with hospitalisation and deaths reduced by a similar percentage.

Professor Milne, from UWA’s Department of Computer Science and Software Engineering, said the team’s highly detailed COVID-19 modelling had highlighted the need to catch increasing transmission rates before infections were widely distributed, with early and robust social distancing contributing to the rapid reduction in virus transmission.

“This published study has provided the hard evidence that going ‘hard and early’ is highly beneficial in an Australian setting and this can now be used to guide both the Sydney and Melbourne outbreak responses,” said Professor Milne, who pioneered high-resolution agent-based disease modelling in Australia. 

“Such measures were found to significantly contain then reduce the epidemic growth rate, and consequential pressure on healthcare resources.”

The UWA disease modelling study on COVID-19 outbreak responses, updated and published in Scientific Reports, ran a range of different social distancing scenarios for the Melbourne 2020 second wave lockdown using sophisticated computer simulation technology. This created a “virtual world” of individuals whose movement and changing contact patterns was captured on a day-by-day basis, with the contact patterns modified by lockdown measures, such as school and workplace closures.

Funded by the Western Australian and Queensland departments of health, the UWA modelling program is an adaption of an established seasonal influenza disease model based on a 270,000-strong population in Newcastle in NSW, and uses early COVID-19 transmission data from Hubei Province in China collected before containment measures were activated.

Professor Milne said the recent UWA disease modelling findings showed definitively that the Victorian Government should have moved to a Stage 4 hard lockdown without going through Stage 3. 

“Hesitancy is understandable,” said Professor Milne. “Long-duration school closure impacts education outcomes, particularly among those from low socio-economic backgrounds. 

“Closure of cafes, restaurants and bars results in under-employment of young adults, and has a knock-on effect on the economy. Closure of service and transport industries results in increased unemployment, with these measures and home isolation impacting the mental health of those affected.

“However our results demonstrate the criticality of the timing of activation, where a slow response to rapid, exponentially growing case numbers allows the coronavirus to spread widely within the population, before the introduction of more robust social distancing measures can take effect.

“It’s the early control that potentially permits lockdown measures to be eased earlier.”

Professor Milne said establishment of a central national co-ordination centre that compared all outcomes of COVID-19 modelling in Australia would ensure the quickest and most effective response to ongoing outbreaks.