An epidemiologist believes it is unlikely Victoria will be ready to end its sixth lockdown late next week and has recommended a more cautious exit than last time.
Victoria’s five-day moving case average is up to 17.4 and the effective reproduction rate is at 1.4, meaning currently every COVID-19 case is infecting almost one and a half people.
Professor Adrian Esterman, an epidemiologist and biostatistician at the University of South Australia, says Melbourne will get on top of its Delta variant outbreaks, but not by August 19 when the lockdown is due to end.
“I would say it’s highly unlikely,” he told AAP on Friday.
“There is a couple of reasons. The effective reproduction number is still quite high – you want to see that get towards one to feel a bit more comfortable – and the moving average is still going up.
“I don’t think that lockdown will finish, if I was the Victorian government, until you’re in single digits and no mystery cases.”
The state has posted 12 mystery cases over the past three days, with about 20 per cent of all new local infections over that span not in isolation while infectious.
Chief Health Officer Brett Sutton said the three straight days of mystery cases filled him with anxiety and remained a particular concern.
“There are two stories here. For those identified chains of transmission, we are absolutely getting ahead. But every new mystery case we are chasing it,” he told reporters.
The state’s sixth lockdown was sparked by the emergence of mystery cases among Hobsons Bay and Maribyrnong residents, just over a week after restrictions were eased in Melbourne.
At the time, Prof Esterman thought the city came out of its fifth lockdown a week too early.
“That doesn’t necessarily mean to say that there’s cause and effect because you can just be unlucky,” he said.
“You have to remember that 80 per cent of infections are caused by 10 per cent of people. So the majority of the infected people only cause none or one infection.
“It’s pot luck if you’ve got a superspreader out there.”
This time around he suggests Victorian authorities wait until daily cases consistently remain below double digits before relaxing rules, predicting that could take another couple of weeks.
“I am optimistic cases will come down and Victoria will get there – unlike NSW,” Prof Esterman said.
“We know that the current lockdown and restrictions attached to it work. We saw it work in the fifth lockdown and we’ll see it work in this sixth one. It will just take a little while yet.”
His basic projection of the NSW outbreak, meanwhile, forecasts local cases in the state will hit roughly 1000 a day in about two weeks.
AAP
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