World news – Victoria’s coronavirus numbers are better than the modelling predicted


Victoria has recorded 45 new cases of COVID-19, which is an increase on yesterday’s tally of 28, with five deaths overnight.

Modelling released to support the Government’s roadmap to reopening had predicted the state would have a 14-day case average of 63 on September 17.

The University of Melbourne and University of New England modelling, which was released by the Department of Health and Human Services (DHHS) earlier this month, was commissioned in part to estimate a safe threshold for reopening.

« That [predicted 14-day case average] number is probably less important than what we were charged with modelling, which was to work out the probability of a third wave by Christmas when you release at different triggers, » Professor Blakely said.

« So that 63 per day was really just to get the model moving but the purpose of the modelling was more about helping provide advice on the trigger releases. »

The modelling used an agent-based dynamic policy model which « imagines a simplified world » where people « move around like pieces on a chess board ».

Each person is given their own characteristics affecting their movement: some are old, some are young, some work, some go to school, some are very infectious when they contract COVID-19 and others are not.

If a person moves into the same square as another person who has COVID-19, the modelling may see them contract the virus.

« If restrictions are eased while the virus is still circulating widely in the community, there is a real risk that infections will rebound — causing restrictions to be reimposed and last much longer, » the report said.

« Actuals always beat assumptions, data always trumps any model, even a robust model that has had input from many experts, multiple universities, » he said.

« By September 28, if we keep going at this rate, we should be less than 20 [new cases] per day and we should be less than a 14-day average of 30 per day, » he said.

Professor Blakely said he was still « not convinced » Victoria would get close to elimination. The roadmap sets the trigger for moving to step 4 as zero new cases for more than 14 days.

But he said the structure of the roadmap was « very good », the steps were « well-defined » and having triggers as well as dates was important.

« That’s a vast improvement than just setting a date and believing that the virus is listening to us and knows the date at which we want it to go away, » he said.

« What we’re all talking about, and by we I mean all Victorians, not just me, is what those triggers should be and there’s a good discussion about that. »

The Premier yesterday said it was important to look at not just the case numbers but the circumstances of each new case, and allow for the passage of time.

But he committed to adjusting the model if required, provided test numbers were high enough to paint an accurate picture of how much virus was in the community.

« If the tail of this thing is more stubborn than we hope, then of course we reserve the right to make the judgement at some point that this is as good as it is going to get so therefore we have to adjust things for that, » he said.

« The opposite is true also … if we finish up ahead of schedule, then we will adjust things. »

But even though Melbourne’s 14-day case average is already within the target range of between 30 and 50, he cautioned against rushing into next step, currently scheduled for September 28.

« We have the option of releasing earlier to the next stage but if we release earlier … we may slow that fall and the really big liberty gains that we get are at the next transition in October, » he said.

« It may be better to stay where we are until September 28 and then get to the next one faster. »

This service may include material from Agence France-Presse (AFP), APTN, Reuters, AAP, CNN and the BBC World Service which is copyright and cannot be reproduced.

AEST = Australian Eastern Standard Time which is 10 hours ahead of GMT (Greenwich Mean Time)


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