Health authorities are considering putting Victoria's coronavirus hotspots in lockdown as the number of new infections in the state continues to grow.
Victoria recorded 49 new COVID-19 cases on Sunday, the highest daily total in the state since April 2 when 68 cases were detected.
Only four of the new cases were linked to known outbreaks, with 26 detected through routine testing and 19 under investigation.
Premier Daniel Andrews said authorities are waiting on the full results of the three-day coronavirus testing blitz in 10 suburban hotspots to come through before deciding on any further measures to contain the virus.
He has not ruled out a lockdown for the worst-affected areas.
"That is not our preference but we'll do it if we need to," he said.
Plans to ease restrictions were put on hold by the state government last week, while the number of visitors allowed at homes was reduced to five.
Victorian Chief Health Officer Professor Brett Sutton said it will not be clear for another five to six days how successful the interventions have been in containing the virus.
"If it continues to increase, I think those are the circumstances where you think about an additional intervention, and especially if it is localised in a particular postcode or a particular suburb," Professor Sutton said.
On Sunday, they announced returned overseas travellers would be forced to submit to coronavirus testing or face an additional 10 days in hotel quarantine.
The move comes after it was revealed 30 per cent of returned travellers had been refusing tests.
Mr Andrews explained many were young children whose parents did not wish them to undergo uncomfortable nose and throat swabs.
"It is not a pleasant procedure," he said.
Less-invasive saliva tests, developed by the Doherty Institute, are now being rolled out.
Health research funded in wake of outbreak
With Australia facing drought, bushfires and now the coronavirus pandemic over the last year, the Morrison government is investing heavily to ensure the mental and physical welfare of the nation.
From July 1, the government is providing $89.5 million over the next three years for the Australian Bureau of Statistics to undertake a comprehensive health survey of the physical and mental health of the Australian population.
The intergenerational health and mental health survey was first announced in the 2019/20 mid-year budget review last December and events since make such work even more essential.
"The survey will provide data to enable Australian governments and other providers of health services to better develop and coordinate health services," the government says.
The cost of the measure will be drawn from existing resources of the Department of Health.
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