Epidemiologist calls for mass testing of Melburnians with no coronavirus symptoms

A leading epidemiologist has called on Victoria’s health authorities to begin wide-scale testing of Melburnians who don’t have symptoms of COVID-19 to prevent a potential third wave of coronavirus.

The number of new cases being reported in Victoria is on the way down and the State Government has indicated that stage 4 restrictions are likely to be eased from September 13.

However, the number of Victorians getting tested for the virus has also been declining, with Tuesday’s daily figure of 10,153 the lowest since the beginning of the second wave in June.

Mary-Louise McLaws, a UNSW professor and World Health Organization advisor, said that without adequate testing the low daily case counts could “potentially be a severe underestimation”.

“Without testing, it’s very difficult to know whether the numbers are low because they’ve got it under control, or the numbers are low because people aren’t coming aboard and being tested,” Professor McLaws said.

The State Government has repeatedly urged people with “even the mildest symptoms” to get tested, but stopped short of testing people without symptoms or another risk factor.

Chief Health Officer Brett Sutton last month said that there was a one in 5,000 chance that someone without symptoms would test positive at any given time.

“So that is a lot of tests that we have to do to find a true case,” Professor Sutton said.

A woman in glass in a home office.
Epidemiologist Mary-Louise McLaws says expanding testing to people without COVID-19 symptoms would be worthwhile.(ABC News)

Ms McLaws said that testing infrastructure now appeared to have more capacity and people at risk or with symptoms could be fast-tracked.

She said “batching”, in which a number of people are tested as one sample to speed up the process, was an option.

With such a high proportion of coronavirus cases having mild or no symptoms, it would be worthwhile loosening the testing criteria further, she said.

“Everybody is asymptomatic for up to the first five days and about 18 per cent of people remain asymptomatic for their whole COVID experience,” she said.

The disastrous consequences of a third wave — combined with the potential long-term health impacts of COVID-19 — meant there was no question the extra testing would be cost effective, she said.

‘Blanket testing is not what we need’

Not all experts agree that wide-scale testing of people with no symptoms is worthwhile.

Maximilian de Courten, health policy lead at Victoria University’s Mitchell Institute, said the proportion of people testing positive was more important than the number of tests being conducted.

“If it’s truly what it looks like — and we all hope — that the community spread is actually going down, doing a blanket testing of everyone, I don’t think gives us much insight,” Professor de Courten said.

He said the downside to mass testing was the expense and potential to clog up the system.

“I wouldn’t agree with going out and testing everyone unless you do a population survey in an area where you have sufficient suspicion there are cases in the community that we have no clue about, and then you basically block the roads and test everyone,” he said.

He said batch testing was difficult logistically when people were being tested in drive-throughs — because if one member of a batch tested positive, then all members would have to be contacted, brought back and re-tested.

“Blanket testing is not what we need,” he said.

“We need intelligent testing, that means it can go down after the community transmission shows signs of really going down.”

That would change if testing was quicker and more efficient, he said.

“Into the future, what we really need is a rapid test, which we still don’t have,” he said.

“Because then you can have a testing station outside each office and while you wait for your results, you just have a coffee.

“If we were testing everyone, let’s make sure that we don’t hit a snag and suddenly results take three days.”

Why are fewer people getting tested?

Professor de Courten said there were a number of possible reasons fewer people with symptoms were getting tested.

He said a good reason would be that fewer people were suffering symptoms similar to COVID-19 because people weren’t going out and catching colds or the flu at the moment.

A bad reason would be that people were avoiding getting tested because they didn’t want to take time off work, despite the State Government offering cash compensation.

“That would be of great concern because that would accelerate them spreading the virus,” he said.

He said widening the testing criteria would not help with those cases because they would not get tested anyway.

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