EXPERT REACTION: Modelling shows combined social distancing measures effective against COVID-19

Embargoed until: Publicly released:
The University of Western Australia has released data showing that social distancing measures such as working from home, self-isolation, and community contact reduction should be highly effective in reducing the number of cases of COVID-19. It found that two most effective social distancing measures were self-isolation and a 70 per cent reduction in community-wide contact, which is defined as any social contact outside of school, work or home. The study has not yet been published in a journal, or peer-reviewed and scrutinised by independent experts. The researchers used computer modelling to evaluate how a range of social distancing measures could stop the virus spreading using the town of Newcastle, in NSW to model spread.

DOI: 10.1101/2020.03.20.20040055

Organisation/s: The University of Western Australia, The University of Sydney

Funder: Competing Interest Statement: Commonwealth of Australia, Department of Health funded program of related research Funding Statement: No funding for this specific research paper

Media Release

From: The University of Western Australia

COMBINED SOCIAL DISTANCING MEASURES PROVE EFFECTIVE IN REDUCING SPREAD OF COVID-19

New world-leading research by The University of Western Australia has confirmed that social distancing measures such as working from home, self-isolation, and community contact reduction are highly effective in reducing the number of cases of COVID-19.

Researchers used computer modelling to evaluate a range of social distancing measures to determine for the first time which strategies were most effective in reducing the peak daily infection rate and resulting pressure on the health care system.

The study, published today in MedRxiv, found that the two most effective social distancing measures were self-isolation and a 70 per cent reduction in community-wide contact, which is defined as any social contact outside of school, work or home.

Research leader Professor George Milne, from UWA’s School of Computer Science and Software Engineering, said both these measures could be further strengthened.

“Given we assumed that only cases are isolated, not the whole family, there is scope to increase the effectiveness of that strategy,” Professor Milne said.

The ability of countries to contain and control transmission of COVID-19 was critical in the absence of a vaccine, he said.

Professor Milne said the modelling suggested that school closure was the least effective single social distancing measure and it was highly disruptive as adults needed to care for younger children.

“Its moderate effectiveness arises from our assumption that children still have contact in the wider community when schools are closed,” he said. “This suggests that combining school closure with even a 30 per cent reduction in community-wide contact will be significantly more effective.”

Using COVID-19 transmission data from the outbreak source in Hubei Province in China collected before containment measures were activated, the researchers adapted an established individual-based simulation model of the city of Newcastle in New South Wales, Australia, which has a population of 272,409.

Professor Milne said simulation of virus transmission in the community model without interventions provided a baseline from which to compare alternative social distancing strategies.

“The infection history of each individual was determined, as was the time of infection,” he said. “From this model-generated data the rate of growth in cases, the magnitude of the epidemic peak and the outbreak duration was obtained.”

Researchers found that both the timing and strength of social distancing measures had a substantial effect in reducing the number of infections in a pandemic situation.

Professor Milne said the timing of activation of social distancing measures was a challenge facing public health authorities, balancing what needed to be done with what was feasible, and this would vary between countries.

“Our modelling gives initial guidance on the relative benefit of a range of mitigation strategies,” he said.

“As the COVID-19 pandemic develops more subtle strategies will need to be evaluated, such as the phased introduction of additional measures if it is found that existing strategies are ineffective in reducing daily case numbers.

“Similarly, modelling will be required to determine optimal strategies to phase the ending of interventions once the epidemic peak has passed.”

Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Associate Professor Adam Kamradt-Scott is an expert in the spread and control of infectious diseases at the Centre for International Security Studies at the University of Sydney

This study arguably validates the Australian Government’s position that school closures are likely to be one of the least effective social distancing strategies to be employed in the current COVID19 pandemic. While we need to ensure teachers are protected, keeping schools open will have the least disruptive impact on children’s education, allow more people to remain in the workforce, and thereby reduce some of the more significant social and economic impacts that we would otherwise see.

To be effective, school closures must be accompanied by other more stringent measures so that children are not interacting in other venues. We have also seen in previous outbreaks that when school closures are implemented it results in a higher rate of teenage pregnancies, less life choices for young women, and higher rates of domestic violence and substance abuse. This is why we need to weigh each measure carefully to ensure the benefits in reducing viral transmission are not offset by other unintended harms.

Last updated: 06 Apr 2020 9:50am
Declared conflicts of interest:
None declared.
Professor Robert Booy is a researcher in child and adolescent health from the Sydney Medical School, University of Sydney and The Children's Hospital at Westmead

Modelling studies such as this are dependent on the assumptions the authors have made. The conclusion that four social distancing measures: school closure; workplace closure and non-attendance; case isolation; and reduced community-wide contact,  can slow the virus spread is encouraging. Given the situation we currently face,  it would have been helpful to separate school closures from the other three measures to clarify this issue. The half way measure we currently have in place, where around half of Aussie kids are at school and half are at home, may actually turn out to be the most protective.

Last updated: 25 Mar 2020 12:43pm
Declared conflicts of interest:
Robert works with most pharmaceutical companies. He does not accept personal payment. His research has been supported by industry as has his attendance at key conferences

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