Updated April 21, 2020 13:57:59

Photo: Chief Health Officer Brett Sutton said many more people would need to be tested if Australia was to eliminate coronavirus. (Reuters: Vasily Fedosenko)

Victorian Chief Health Officer Brett Sutton says eliminating coronavirus across Australia is possible if testing is ramped up to include everyone, regardless of symptoms.

Professor Sutton told ABC Radio Melbourne seven more cases of coronavirus were confirmed overnight in the state, and that low numbers of new infections across the nation indicated Australia was on its way to zero cases.

"We've gone earlier [in taking action] than most countries with comparable rates anywhere in the world and I think that's why we're in the position we're in," he said.

He said in comparison to New Zealand, "we're very much on the same pathway".

"Elimination is actually a viable option for us here in Australia so I wouldn't rule it out, in terms of being in as optimistic a position as New Zealand."

He said elimination would only be possible if testing was expanded to people without symptoms.

"I think there are lots of complexities with eliminations. It does mean having zero cases across the entire country. It would need a surveillance system which would mean no cases of transmission anywhere," he said.

"That would mean lots of testing, lots of individuals coming forward potentially trying to work out if there's asymptomatic transmission."

Professor Sutton said environmental testing would also need to be done to figure out if the virus was present in sewage.

"That might be able to tell us if [the virus is still present] even if we haven't detected cases or more optimistically if we can't find it anywhere."

He also said Victoria could see daily new cases drop to zero by June as the majority of positive cases continued to be from people who had recently arrived from overseas.

Photo: Victorian Chief Health Officer Brett Sutton said Australia was "on the same pathway" as New Zealand in trying to eliminate the virus. (AAP: Stefan Postles)

"We don't know how well people will manage this but if we can carry on with the behaviours that we've been doing in terms of the physical-distancing measures and staying at home, that's entirely possible for us," he said.

Professor Sutton said cases may not remain at zero every day and warned there were some settings such as aged care homes that were vulnerable to local outbreaks of the virus.

"But if we can get to a typical day where we get zero or one case I think that's entirely feasible over the next month or two."

Cases of seasonal flu drop but rapid increase could be on way

Meanwhile, doctors have attributed a dramatic drop in national influenza cases to social-distancing measures and an uptake of early flu vaccinations.

Just 99 laboratory-confirmed influenza infections have been reported so far this month, compared to 18,377 recorded in April last year, according to federal health data.

The number of confirmed infections in January and February this year was above average before the coronavirus shutdown and social-distancing measures came into effect in March, suggesting the country was headed for a significant flu season.

Australian Medical Assocation (AMA) South Australian president Chris Moy said social distancing and early flu vaccinations had temporarily suppressed the spread of the flu.

Photo: A significant decline in cases of seasonal flu has been partly attributed to more people receiving the flu shot. (Supplied)

"Influenza is passed on in the same manner as COVID-19. And therefore the current social isolation and social distancing is going to reduce the spread of it between individuals," Dr Moy said.

"The other thing that's been a factor is the relatively early vaccination of a lot of individuals compared to previous years, so we're in a slightly artificial situation at the moment and holding it down."

The drop in infections comes amid unprecedented demand for the flu vaccine, with three times as many people receiving the vaccine compared to last year.

Breaking down the latest news and research to understand how the world is living through an epidemic, this is the ABC's Coronacast podcast.

However, Dr Moy said the suppression of the flu would be temporary, with the easing of restrictions likely to lead to higher infection rates.

"As soon as you start to relax things in terms of social distancing and social isolation, not only will you increase the chance that COVID will take off but influenza may also take off," he said.

"It will not just be a slow increase, it will possibly be a rapid increase.

"We don't have a good idea about the relative infectivity of the current influenza strains, and whether they are very serious compared to previous years."

Dr Moy recommended vulnerable people talk to their doctor about potentially getting a second top-up vaccination as the season progressed.

"Particularly those individuals who have immunosuppression or had the vaccination during a time of immunosuppression, it would be worth talking to your doctor about whether it's worth having a second vaccination."

Victorian institute leading international trial of potential COVID-19 treatments

Melbourne's Doherty Institute is leading a trial of two existing drugs' effectiveness in treating COVID-19 in more than 70 hospitals across Australia and New Zealand.

The trial will test whether the HIV drug Lopinavir/Ritonavir and the Malaria and arthritis medication Hydroxychloroquine are effective at safe dosages.

Researchers hope to have 2,000 patients participate in the 12- to 18-month-long trial, which means most Australians who get the disease can take part, however people in intensive care will not be included.

Overseas studies have shown the two drugs have an effect on the new coronavirus in labs, but it is unclear how effective they are in the real world.

The trial's principal investigator, Steven Tong, said the team was monitoring overseas studies, and could include other drugs in the Australian study in the future.

"Once we get the infrastructure up and going we can adapt, so if it is showing one of these treatments is completely ineffective or harmful, we can drop that therapy," he said.

"And it allow us to now try different therapies, experimental therapies, within a safe and ethical framework."

'Family violence is not going to reduce during this period'

Victoria's Police Minister Lisa Neville announced the beginning of Operation Ribbon to combat an expected spike in family violence.

"We haven't seen, nor have agencies seen, a significant increase in family violence cases," Ms Neville said.

"We remain concerned that there are some heightened risks out there and also we remain concerned that for many making that phone call is also very difficult."

She said Operation Ribbon was a proactive measure by Victoria Police to reach out to victims of family violence and check that perpetrators were complying with family violence management plans and court orders.

Photo: Police officers will be proactively contacting victims of family violence and perpetrators as part of Operation Ribbon. (ABC News: James Oaten)

"Family violence is not going to reduce during this period," Ms Neville said.

"Victoria Police members will be reaching out to you. Take that helping hand ... if you need it.

"We know family violence remains a heightened risk in this period of self-isolation — that is why this operation will be so critical."

Victoria Police Assistant Commissioner Shane Patton said detectives had spoken to 241 victims of family violence and 106 perpetrators in the past two weeks.

Thirteen of those offenders were remanded in custody, seven were bailed and four were subject to a summons.

Ms Neville also said there had been a significant decline in the number of people calling the police assistance line.

Calls had dropped from 2,400 calls a day last week to 1,300 a day this week.

Victoria Police issued another 89 fines in the 24 hours to 11:00pm Monday for suspected breaches of physical-distancing rules.

The owner of a massage parlour in Frankston was fined after two workers were found in the venue. The employees were also issued with infringement notices.

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First posted April 21, 2020 10:04:37