Why Brisbane's COVID cluster is of 'national concern'

Queensland Premier Annastacia Palaszczuk has called for an immediate overhaul of Australia's quarantine system as a highly contagious UK virus variant cluster grows inside a Brisbane hotel.

Six cases of the mutant strain of COVID-19 have been linked back to one floor of the quarantine hotel in Brisbane's CBD and authorities do not know how it has spread across rooms.

Ms Palaszczuk said the risk surrounding the new cluster has "really stepped up to that next level" because the variant, known as B.1.1.7 or 501Y.V1, is more contagious.

Ambulances at the ready to transport hotel quarantine guests from the Hotel Grand Chancellor in Brisbane on Wednesday. Credit: Matt Dennien

"We're learning more and more about this virus every day and it is a completely new strain, so it is highly infectious and I just think everybody in Australia needs to be aware that things are not as normal as they were under COVID," she said.

"It is of national concern, not just to Queensland, but everywhere else."

Ms Palaszczuk said she would brief her interstate counterparts on Wednesday after a meeting of the state's chief health officers.

"I think we need to immediately look at the way in which we are handling people coming into the country, international arrivals also, too, looking at the quarantine hotels that they are going into," she said.

"Of course, we have to put in additional precautions and we are doing that immediately, but what we are dealing with here is something that we've never had to deal with before."

National cabinet last week agreed to cut the cap on Queensland's overseas arrivals from 1400 each week down to 500.

"So the first good step is that the number of arrivals has been decreased, " Ms Palaszczuk said.

"But also too, it's highly contagious, the fact that all of these six people were on the seventh floor ... How did it get transmitted? Was it in the airconditioning? Was it movement? Was it picking up something? We just don't know those answers yet."

Two investigations into of the state's hotel quarantine system are under way, one led by police and the other by health officials.

Officials have trawled through CCTV footage but have yet to find any point of transmission from the original case to a hotel cleaner or to a father and son who were quarantining on the same floor.

Chief Health Officer Dr Jeannette Young said the investigation would examine whether the virus could have been spread through airconditioning vents or by flushing toilets.

At this stage, only two of the six cases were mingling in the community while infectious: a hotel cleaner and her partner, whose positive tests sent Brisbane into lockdown last weekend.

Ambulances began trucking 129 people still in quarantine at the Hotel Grand Chancellor to new hotels on Wednesday.

A further 226 people who worked in the hotel since December 30 will be placed into quarantine, as will another 250 quarantined guests who have left the hotel.

Queensland recorded no new locally acquired cases of COVID-19 on Wednesday although two people tested positive in hotel quarantine.

They were not staying at the Hotel Grand Chancellor, which is the epicentre of the state's latest cluster, but genome testing is under way to determine if the pair are infected with the UK strain.

How the six cases became infected

December 30: A man who had come to Brisbane from the United Kingdom with the mutant strain tests positive. He then infects his partner who was staying in the same room, on level seven of Hotel Grand Chancellor in Brisbane's CBD.

January 6: A hotel cleaner tests positive for the virus. The 22-year-old had returned a negative test on December 29 but authorities believe she was unknowingly infectious in the community for five days.

January 8-11: Brisbane goes into lockdown. No new cases are detected in the community.

January 11: The cleaner's partner tests positive. He was infectious in the community for two days before he went into isolation on January 7.

January 12: A father and son who had returned from Lebanon test positive to COVID-19 on day 10 of their hotel quarantine stay. They were housed on level seven of the Grand Chancellor.

January 13: Heath authorities evacuate the Grand Chancellor.