Queensland has confirmed two Covid-19 cases after it was revealed a Melbourne case breached lockdown restrictions to go on a road trip across two other states.

One of the cases, a 44-year-old woman who travelled from Melbourne, was confirmed yesterday, with her husband now also testing positive.

The woman and her partner left Victoria on June 1, four days after a statewide lockdown had come into force.

The pair travelled by car through regional NSW and into Queensland, stopping at multiple venues along the way.

The woman tested positive to Covid-19 at Caloundra on the Sunshine Coast on June 8 after joining relatives there, though it is understood she had been experiencing symptoms since at least June 3.

The Queensland case numbers came shortly after Victorian authorities revealed four new Covid-19 infections had been recorded.

The cases came from the same household but the source of the infections is still not known, sparking concerns it could put the planned lifting of restrictions across Melbourne at risk.

Queensland's chief health officer Dr Jeanette Young said it appeared both of the state's cases were towards the end of their infectious period.

However, she said it was still extremely important for residents to come forward and get tested.

"It's still there, and I still need everyone to come forward who develops any symptoms at all who lives in the Sunshine Coast, or Goondiwindi or Toowoomba — it's very, very important," she said.

"We've seen a lot of testing already started. That needs to continue, just so we can make sure that there hasn't been any transmission out there."

So far authorities have identified 17 immediate close contacts, with three of those testing negative to the virus.

Two of those negative results came from the parents that the couple were staying with.

It appears it was sheer luck that the infected Melbourne woman was caught, with the Courier Mail reporting the woman only got tested because her partner needed a negative covid test result for work purposes.

The Melbourne woman is being managed by Sunshine Coast University Hospital staff and her partner is also in hospital being monitored.

Health authorities are now facing a "challenging" next few days as they scramble to retrace the woman's steps.

Burnet Institute epidemiologist Mike Toole said high testing rates were "critical" in this situation in order to locate any potential outbreaks.

"It's always a concern with someone who is infected with the virus has travelled so widely through three states," he told Sunrise.

"This will have put all of the case finding teams on alert. It's quite challenging."

Professor Toole noted that the woman only appeared to have a small amount of virus in her throat and nose, however, he warned she could have been more infectious when she set off on her journey.

"Keep in mind she left Melbourne a week ago and may have had more virus when she went to all those exposure sites," he said.

Theory emerges on how couple went undetected

As all three states scramble to track the couple's movements, questions have been raised about how they managed to escape lockdown in the first place and cross into two new states without being caught.

Melburnians in lockdown were banned from travelling 5km from home and Victorians have been banned from entering NSW unless they live in border communities.

Queensland declared all of Victoria a hotspot on May 28, meaning anybody who had been in Victoria within 14 days of attempting to enter Queensland faced mandatory 14-day hotel quarantine.

The couple took a route through regional NSW, stopping at Gillenbah, Forbes, Dubbo and Moree before crossing the border into Queensland at Goondiwindi — a suburb on the MacIntyre River, 350km south west of Brisbane.

According to the Courier Mail, one theory about the couple's route is that they chose to cross the border at Goondiwindi because the focus of police patrols were on the border at the Gold Coast.

Queensland Police Deputy Commissioner Steve Gollschewski refused to be drawn on the question of whether the pair "lied on her declaration form", saying the circumstances around their travel would be investigated.

So far 20 exposure sites linked to the Melbourne woman have been identified by NSW and Queensland health authorities.

In NSW a number of cafes, pubs and motels across Dubbo, Moree, Forbes and Gillenbah have been identified as venues of concern.

In Queensland a McDonalds, Kmart, shopping centre and IGA are among some of the venues identified across Goondiwindi, Toowoomba, Moffat Beach, Kings Beach, Caloundra, Buddina and Baringa.

Melbourne's lockdown to ease tonight

Melbourne residents are set to emerge from a tough two-week lockdown tonight, with Acting Premier James Merlino announcing "significant steps" to easing restrictions on Wednesday.

Fromm 11.59pm tonight Melbourne will be able to move to "most of the same settings" currently in place across the rest of the state, with regional Victoria also moving to further ease restrictions.

Melburnians will be restricted to a 25km travel limit, with the only reasons to travel further being for work, education, caregiving or getting vaccinated.

The ban on visitors to households will remain but outdoor gatherings will be increased to 10 people.

Masks will no longer be required outdoors unless you can't maintain a 1.5 metre distance, though they will remain a requirement in indoor settings.

Travel to regional Victoria is still banned.

For regional Victoria the some of the changes include allowing two adults per day, plus their dependants, as household visitors, with public gatherings also increased to 20 people.

Restaurants and cafes can open to a maximum of 150 per venue for seated service, including up to 75 allowed indoors.

Religious ceremonies will be capped at 150 per venue, with no more than 75 people allowed indoors. Funerals will be limited to 75 people and weddings will be capped at 20.

Victoria's chief health officer Professor Brett Sutton warned residents that they were "still not back to normal" and urged people to continue to be on high alert for Covid-19 symptoms.

He said there could still be undetected cases within the community, making high testing rates so important.

"It is an awfully painful period. I have always had in mind that we need to do what is required to make sure that we get back down to zero. There is really no alternative," Professor Sutton said.

"Our national strategy of aggressive suppression is there for a reason. If you do not get to zero, there is no grumbling along with one or two cases. This started with one case in Wollert that has led to almost 100 cases over a period of a few weeks. So we absolutely have to drive it back down to zero."