Health authorities in Queensland are grappling with multiple different COVID-19 outbreaks, including one mystery case that has sent contact tracers racing to find out how the virus was spread.
Five more cases of community transmission were detected on Saturday and three in hotel quarantine.
The new cases included a 29-year-old Brisbane man who travelled to Eumundi on June 27, a woman in her 50s from Everton Park in Brisbane and a baggage handler in his 50s at the Brisbane Domestic Airport.
A Sunshine Coast man in his 50s, was confirmed to have the virus late on Friday afternoon.
The detection of the case did not stop lockdown being lifted for Sunshine Coast residents last night.
Authorities are now dealing with outbreaks on multiple different fronts, including cases linked to:
- The Prince Charles Hospital (Delta strain)
- FIFO workers from The Granites gold mine in the Northern Territory (Delta strain)
- Brisbane International Airport (Delta strain)
- A Virgin flight crew member (Delta strain)
- The Portuguese Family Centre restaurant (Alpha strain)
The state's Chief Health Officer Jeannette Young said she was not overly concerned about undetected cases in the community due to the high rate of testing.
On Saturday, of the five new locally aquired cases, three had been linked to known clusters.
Dr Young believed the Delta cluster linked to the the NT mine workers was now "under control" and "we don't need to worry anymore".
She was also confident about the the Virgin flight crew cluster, which was also the Delta strain.
"Most concerning" is the Portuguese Family Centre cluster of the Alpha variant with 17 cases so far.
Due to it's long incubation period, that cluster is still generating cases.
"It's all about if you have a super spreader," Dr Young said.
"We've had other Alpha-related outbreaks and there's not been a superspreader and we've got on top of it very quickly. This time we clearly have."
Deputy Premier Steven Miles said it was important that everyone, particularly in the south-east, assumed they may come in contact with the virus.
"For the first time in a long time, though, there could be cases in our community that we don't know about," he said.
Townsville city, Palm Island and Magnetic Island were plunged into lockdown, along with 11 local government areas in south-east Queensland, after an unvaccinated hospital worker with the Delta strain travelled to north Queensland.
"Those people only just came through for a short time in Townsville and then went to Magnetic Island and they've managed to not go out broadly," Dr Young said.
"They've been on holidays there, so they've remained there.
"The amount of testing that has been done up there has been absolutely fantastic, so that's why I'm pretty confident."
Testing is best defence against community spread
Griffith University virologist and research leader Lara Herrero said there was always a possibility of undetected cases in the community.
"There's always that possibility [and] it's maybe slightly greater now that we have got detected cases," Dr Herrero said.
"There is still a best attempt at hotel quarantine but leaks do happen and we should always be aware that community transmission that's undetected may still be going on."
Dr Herrero said getting tested and practising social distancing was the best defence against unknown community spread.
"I think that we have become a little complacent with that; certainly now it's winter.
"On top of that, I think we have become complacent with our social distancing and our hand hygiene.
"We need to go back go that and remember that it is critical in stopping the transmission.
"And don't underestimate that there might be something out there."
