By Nick Carne
Social distancing can help curb COVID-19 in Australia in three months, as modeling at the University of Sydney suggests.
However, this will only happen if 90% of the population meet the requirements and restrictions. If less than 70% do this, according to Mikhail Prokopenko and colleagues, experts in complex systems, this will be an unproductive measure.
This requires the continuation of two other interventions – international arrival restrictions and case isolation (with increasing testing and monitoring resources).
“There is a clear compromise,” says Prokopenko. “Stricter measures that were imposed earlier would reduce the length of time that this disease affects our lives. On the contrary, loose protocols could mean a longer, longer and more ineffective fight against COVID-19. “
Prokopenko added that society would have to endure a few more days for each day that the stricter measures to distance themselves were delayed as part of a longer repression policy.
“The longer we delay the climax, the more time our healthcare system has to prepare by accessing more resources, such as intensive care beds, ventilators, antivirals, and trained healthcare professionals.”
The study also found that while school closings have the potential to compensate for 10% of the lack of social distance, the pandemic would only be delayed by two weeks.
School closures did not significantly reduce new cases in older adults, but did slightly increase the proportion of new cases in children around the height of the pandemic in Australia.
The Prokopenko team used a simulator with more than 24 million software agents, each with attributes of an anonymous person such as age, gender, job, susceptibility and immunity to disease.
Contact rates in various social contexts – such as households, household clusters, local neighborhoods, schools, classrooms and workplaces – are integrated into the program. The set of generated agents captures the average characteristics of the real population and is calibrated to the 2016 Australian Census data in relation to key demographic statistics.
“This model is calibrated to reproduce several features of COVID-19 transmission, taking into account the number of reproductions, the length of the incubation and generation periods, the age-dependent attack rates and the growth rate of the cumulative incidence during a persistent and unrestricted local transmission. The researchers write in an article that is available on the pre-print server arXiv.
“An important calibration result is the age-related proportion of symptomatic cases, with this proportion accounting for a fifth of this proportion in adults. We then apply the model to compare different intervention strategies, including restrictions on international air traffic, case isolation, social distancing with different levels of compliance, and school closings.
“The interactions lead to the transmission of the disease from infectious to susceptible people. Given the contact and transfer rates, the simulation calculates and updates the states of the agents over time, starting with initial infections that were performed at international airports across Australia. ”
The researchers say that the next phase of the work will address the study’s limitations, including more detailed implementation of the natural course of the disease, incorporation of more recent ABS data, incorporation of the quarantine strategy for the affected households, and a more refined school closure strategy.