A parent may have infected an already sick newborn baby with coronavirus while visiting another child in ICU, according to reports.
A three-week-old baby, as well as two parents and a healthcare worker in the neonatal intensive care unit at the Royal Children's Hospital in Melbourne had tested positive on Monday.
Nine News reports a parent of a different child - who visited the ward but was not symptomatic at the time - is among those to have tested positive.
All other babies in the unit have so far tested negative.
Victoria's Health Minister Jenny Mikakos confirmed while the hospital was waiting for the test results of one more baby, all others appear to not have contracted Covid-19.
"We've had a very challenging set of circumstances in the last 24 hours at the Royal Children's Hospital," Ms Mikakos said.
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"It is very good news, very positive news that I wanted to share with the community, because I know that this particular incident is one that would have caused a great deal of distress to many."
Dr Sarah Whitelaw, from neighbouring Royal Melbourne Hospital, said the newborn case was "extremely concerning".
"For us over the last couple of weeks, we have been very confronted by the number of young, very sick people that we are seeing with Covid and the increasing numbers of those," Dr Whitelaw told the Nine Network's Today programme.
"Unfortunately the virus doesn't discriminate. Some very young children will get the virus and some of them will get sick."
While Paediatrician and Chief of Medicine at the Royal Children's Hospital, Associate Professor Tom Connell told 3AW symptoms among babies to look out for include fever, sneezing, fast breathing and changes in mood or behaviour.
Victoria, Australia's second most populous state, where Melbourne is situated, reported 384 new Covid-19 cases on Tuesday, down from the record 532 it reported on Monday but still at levels alarming health officials.
Australian Prime Minister Scott Morrison cut short a planned interstate tour to focus on the country's coronavirus crisis on Tuesday, citing a "very complex" outbreak in aged care homes in Melbourne.
