Victoria on-track to meet October 26 threshold daily case average early: epidemiologist
New independent modelling shows Victoria is on-track to meet its coveted threshold of five or fewer daily cases as early as next week — prompting calls for Melbourne’s curfew and 5km radius to be lifted earlier than planned.
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Victoria’s daily coronavirus cases are predicted to be fewer than five as early as the middle of next week.
Independent modelling by University of South Australia Prof Adrian Esterman suggests if daily case numbers continue to fall, we may meet the October 26 threshold of five or fewer cases over a 14-day average before the planned date.
Prof Esterman’s prediction is almost one month earlier than government modelling and what’s outlined in Premier Dan Andrews’ road map out of restrictions.
The Biostatistics and Epidemiology chair also said he wouldn’t be surprised to see five or fewer cases earlier than October 26.
On Wednesday, Melbourne’s 14-day rolling average has dipped below 30, now standing at 29.4. On Tuesday, that figure fell to 32.8 from 34.4.
Prof Esterman uses his own modelling to predict case number trends, while the government uses different, ‘incredibly complex’ modelling.
Prof Esterman uses the curve of a graph to determine a trend in daily case numbers and looks for a linear or exponential decline.
A linear decline shows a downward trajectory until the line reaches zero and exponential shows a slow, curving of the tail which won’t reach zero.
Here is the 14-day average situation. The curve is somewhere between linear and exponential at the moment. pic.twitter.com/dw0NVZ8Qgi
— Professor Adrian Esterman (@profesterman) September 22, 2020
Prof Esterman says the Victorian coronavirus curve appears to take both linear and exponential traits and would know more about the trend in the next few days.
“An exponential decline fits the data extremely well, but now we are getting to the tail end, the data is following a linear end,” he says.
“If it stays on the exponential curve, (we will meet five or fewer cases on a rolling 14-day average) by 21 October and if it’s linear we will reach that in a fortnight, but in reality it will fall somewhere in between.”
“While the (health department) uses a different concept, we will end up with the same results.”
Prof Esterman says there is no reason why the state government couldn’t ease some Melbourne restrictions — like the curfew or 5km radius — as early as this weekend.
“I think the government shouldn’t be taking an extremely rigid approach to the data,” he said.
“They should be looking at every single restriction and make a judgment on safety.”
However, Prof Esterman said moving forward one entire step this weekend wouldn’t be safe.
“If you moved to the next step this weekend, it would be a risk. I think it’s perfectly safe to relax some restrictions.”
Deakin University Epidemiology chair Prof Catherine Bennett said we could meet that five or fewer daily cases threshold by early or mid October.
“We’re all tracking really well and if we keep tracking this way and persist with these figures under 20 (cases per day), it’s still possible we could meet that under 5 target, maybe early in October,” Prof Bennett said.
When asked whether she saw a danger in opening up earlier than expected, Prof Bennett said:
“I wouldn’t suggest we do anything today, perhaps take this week and see where we go with the numbers.”
Between May 18 and May 31, two weeks before Victoria first eased into stage 2 restrictions, the state’s rolling daily case average was 6.36.
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