Wastewater testing has identified possible undiagnosed cases of COVID-19 in Queensland.

The state on Saturday reported there were no new cases of coronavirus and four active cases.

But more diagnoses could be lurking.

“Samples taken at the Sandgate wastewater plant on (October) 12 and the Maroochydore and Wynnum wastewater plants on the 13th both returned positive results for virus fragments,” Deputy Premier Steven Miles said.

The plants are in suburban Brisbane and Maroochydore is on the Sunshine Coast.

“It could, of course, be someone who’s recently had the infection and then has gone to those places, so they’re not infectious but they’ve recovered, but they’re still shedding virus,” Chief Health Officer Jeannette Young said.

“But it could, of course, be a person that we’ve not picked up, that’s out there in the community.”

Health authorities encourage people to get tested if feeling unwell and there have been 4722 tests conducted across Queensland in about the past day.

It’s more than a month since the state has had an infectious COVID-19 case in the community.

Wastewater testing from Townsville which previously showed virus traces has recently shown to be clear.

And a woman from Townsville who tested positive in Melbourne and had travelled to Brisbane and Cairns and Canberra, has tested negative.

As Queensland stretches its period without community transmission, restrictions on social gatherings are being eased.

Dancing is permitted at weddings and aged care residents are allowed to take excursions.

Gatherings of up to 40 people are permitted at homes and in public places.

“Up to 40 people at a time will be able to dance at weddings and residents at aged care facilities and nursing homes will again be able to go on excursions to the beach, to play bingo,” Dr Miles said.

Year 12 students will also be able to dance at end-of-the-year events with a COVID-safe plan.

Despite recent reassuring test results and the easing of restrictions, Dr Young said Queensland will have more cases of COVID-19 and urged caution.

“It’s really important that people should just have a mask with them wherever they are,” she said.

“And if they can’t maintain social distancing, just pop that mask on.

“It sort of makes sense. And it prepares us for when we do get the next case. Because as I keep on saying, we will get another case of COVID-19 in Queensland, of course we will.”

-AAP