Epidemiologists are cautiously optimistic Victoria’s daily COVID-19 cases are starting to decline, but Premier Daniel Andrews has warned there is no “magic number” the state must reach before restrictions will be eased.
On Monday, the number of new daily cases fell to 322 in Victoria.
It’s the lowest point in the past 10 days, during which time figures have jumped between 400 and more than 700.
Mr Andrews said he understood “everyone wants to know when is this going to end,” but added: “We’ve all got to be careful not to be getting ahead of ourselves.”
He said there was no “magic number” that would allow Victoria to ease restrictions.
“I can’t give you a number,” he said at the daily press conference on Monday.
But epidemiologists are watching the numbers closely to identify trends.
Coronavirus cases need to hit double digits
Mary-Louise McLaws, an epidemiologist and World Health Organization (WHO) adviser, told the ABC she would be comfortable seeing restrictions ease when Victoria’s figures were in double digits.
But masks would need to remain until the state was recording single digits on a daily basis.
“At the moment Victoria’s numbers are slowing, it doesn’t feel like it is, but the growth has slowed and you will start to see a decline,” she said.
Professor McLaws said her “red alert” was when cases hit more than 100 total active cases over two weeks.
If each case had 10 contacts, that meant contact tracers had to track down 1,000 people over a 14-day period.
She said Melbourne and regional Victoria were “far off” any reduced restrictions over the next five weeks.
Professor McLaws said from a “proactive, epidemiologist’s point of view” she would not begin lifting restrictions until there were fewer than 100 active cases over two weeks.
She said the daily curfew in Melbourne and rules around masks would be the last restrictions to be relaxed because they “worked so well”.
“But I don’t have to try and balance the economy,” she said.
She said she would not be surprised if more people started to go back to work before the mandatory use of masks was eased off.
She also said it was possible Victorian authorities could be looking at cases in aged care separately from all other areas of the state.
“That triple-digital number is largely being driven by aged care,” she said.
Experts want at least five days of consistent case numbers
Infectious diseases expert Sanjaya Senanayake agreed fewer than 100 cases over a two-week period was what Victorians should be aiming for.
“I’ll be happy when we see consistent, low numbers that continue to drop, but there’s no magic number for me,” he said.
“It will fluctuate. So you want to see a pattern … a good five days of a consistent number of cases.”
But he added the number of mystery cases — community transmission infections with an unknown source — was the “really important” number.
Victoria currently has 2,863 mystery cases.
Dr Senanayake said the issue was not just about avoiding overwhelming hospitals, but also about keeping contact tracing efforts at a manageable level.
Marc Pellegrini from the Walter and Eliza Hall Institute told ABC Radio Melbourne “most people would be comfortable with numbers in the 10s” at the end of the six-week lockdown.
“We’d certainly want to see a fairly rapid turnaround,” Professor Pellegrini said.
“The numbers at the moment are just way too high so the contact tracers just don’t have capability to reach out to everybody in a timely fashion to stop transmission.”
Dr Senanayake said it could take up to four weeks to really see a drop in daily cases.
He said the issue now was about whether Victoria aimed for elimination — 28 days without a mystery case.
“We should go, potentially, for that elimination model. I think that’s what we should aim for,” he said.
But he warned it might take many, many weeks to get there.
Stage 4 restrictions are going to ‘crash the numbers down’
Professor Tony Blakely said the question of Melbourne reopening depended on the goal.
He agreed if the aim was elimination, the number of daily mystery cases would need to be very low.
He was still modelling the exact number, but suggested five or fewer on average per day would be necessary before easing out of stage 4 into stage 3.
However, if the aim was suppression, Professor Blakely said Melbourne might tolerate higher numbers before opening up.
Despite being a proponent of elimination, he said living relatively normally with cases in the 10s might be possible, pointing to examples of other nations using a suppression strategy.
“Our major concern is that it’s very hard to live with the virus and it will just keep coming back to you in wave after wave after wave,” Professor Blakely said.
He said that would require better contact tracing, testing and surveillance and vigilance with masks.
Professor Blakely added that South Korea provided facilities for people who had tested positive to isolate and people were visited twice a day, not just for enforcement, but to check they had everything they needed.
Both Victoria and NSW would have to pursue elimination for it to work, he added.
One number Professor Blakely is keeping a close eye on is the number of cases in regional Victoria, where the more lenient stage 3 restrictions are in place.
“I would be watching the mystery cases and regional Victoria much more closely,” he said.
Professor Blakely said stage 4 restrictions were going to “crash the numbers down” in the coming weeks.
“It’s going to be steep, because we’re already seeing these numbers start to go down quite quickly now. And stage 4 hasn’t really even kicked in yet.
But he feared Victoria’s curve was unlikely to flatten out and would remain above zero for some time.
“There will be parts of society, the casualised workers in the essential industries, which are harder to get to and they won’t have their transmission stopped as much as amongst the rest of us who are at home,” he said.
“There could be a long tail here that’s hard to get rid of.”