Covid 19 coronavirus: No new local cases in Queensland as NSW cases soar

Anti-lockdown and anti-vaccination activists and protesters march down George St in Sydney, Australia. Photo / Getty Images

While Queensland recorded no new locally acquired Covid-19 cases on Tuesday, the state's health authorities are warning it's "far too early to relax" just yet.

Acting Premier Steven Miles said the lack of new cases was an "excellent result" given the "sheer number of risks" the state is monitoring.

But, given the incubation period of Covid-19 can be up to 14 days, chief health officer Dr Jeannette Young says the state can't let its guard down just yet.

The Sunshine State has two major concerns: a vaccinated Gold Coast man who returned from China and tested positive almost two weeks after he left hotel quarantine; and a Qantas flight attendant who brought a Sydney man into the state despite him being a close contact of a NSW case.

More than 2000 people have been placed into quarantine as a result of both threats.

Young said people needed to continue to wear masks, because she "genuinely" believed they had made a difference in not seeing large cases linked to the infected people.

"I am still very, very worried about the other two individuals, one who came up from Sydney to Ballina and was picked up at Ballina and then came into Queensland with that other person," Young said.

When asked whether she was surprised that there hadn't been any further cases linked to the duo, Young said it was still "too early".

"We're still within that 14 days incubation, we know that although Delta tends to create cases early, it still has cases up to 12, 13 days later," she said.

Chief health officer Dr Jeannette Young said it was an "incredible" result that no cases had been recorded in Queensland on Tuesday. Photo / Getty Images

"So it is far too early for any of us to relax."

Deputy Commissioner Steve Gollschewski said police were "satisfied" they had all the information they needed from the duo to "undertake comprehensive contact tracing".

"Our investigation into any breaches will be concluded later today and we'll be able to advise what happens with that then," he said.

Meanwhile, the returned traveller's genomic sequencing has linked the source of his Delta infection back to the hotel he quarantined at.

He began developing symptoms on July 15, but was not tested until he visited his GP on the Gold Coast for an unrelated matter on July 23.

So far his family has tested negative.