Queensland has entered its fourth COVID-19 wave with authorities recommending masks in certain settings from Friday.
Premier Annastacia Palaszczuk told state parliament there had been an increase in active cases in the past week and a doubling in the number of COVID-19 patients in hospitals.
She said Chief Health Officer John Gerrard had advised the state's traffic light COVID-19 advisory system should switch from green to amber.
"It means that it is recommended that we should wear a mask in healthcare settings, on public transport and rideshares, indoors where you cannot socially distance and if you are around people who are vulnerable to COVID," Ms Palaszczuk said on Thursday.
"This applies especially to older members of community and those at risk," she said.
"[The measures] are effective as of tomorrow."
'Soup of variants' spreading across Queensland
Dr Gerrard said there was a "soup of variants" spreading around the state, with no clear dominant strain yet.
"We are seeing growth in XBB and BQ1… and BQ1 does seem to be growing particularly quickly in Queensland at the moment," he said.
"It is the same strain that is growing very rapidly in the United States and has spread widely across Europe."
The peak of this wave is expected to occur prior to Christmas but its shape remains unknown.
Dr Gerrard said the previous three waves had peaked between five and six weeks from the onset.
"That would put a peak somewhere around the 12th or 19th of December," he said.
However, information from overseas suggests this wave could be shorter and sharper, with a peak closer to the beginning of December.
Incoming 'higher rate of transmission'
Ms Palaszczuk said there were 105 COVID-19 patients in the state's hospitals on November 3, compared to 203 on November 10 with a 58 per cent increase in the number of active cases in the past week.
Last week, there were 3,919 active cases and on Thursday there were 6,199.
"The fourth wave that we have been expecting now we believe has arrived," Ms Palaszczuk said.
"No-one should be alarmed. We have been living with this virus for a long time and Queenslanders know what to do."
Health Minister Yvette D'Ath said the change in COVID-19 risk alert did not mean that any enforceable directions were being issued by the Chief Health Officer (CHO).
"Instead, it means that the Chief Health Officer is indicating to the public that we need to raise our level of alertness, and be prepared to take measures to protect ourselves from a higher rate of community transmission," she said.
Ms D'Ath said the CHO had also advised that people should take a rapid antigen test (RAT) if they were experiencing any symptoms, and any household close contact of a positive case should do a RAT every two days.
"I encourage all Queenslanders to take this advice," Ms D'Ath said.
"We know that some of the best protection against this virus comes from ensuring that we are fully up to date with our booster doses.
"For any person who hasn't had their third or fourth dose and is eligible to do so, I implore you to head down to your local GP or pharmacy and protect yourself in anticipation of this forthcoming wave."
Fourth Omicron wave set to be less severe
Dr Gerrard said his biggest concern ahead of the peak of the fourth Omicron wave in Queensland was the number of people older than 50 who were not up to date with their COVID vaccinations.
"We know that being up to date with vaccinations protects you from hospitalisation and death," he said.
"There are significant numbers of people who are still not up to date."
Dr Gerrard, who began as the state's Chief Health Officer last December, had COVID himself last month.
He said with "a high degree of hybrid immunity" in the community — based on the number of people who have been vaccinated and recovered from COVID — he hoped the latest Omicron wave would be less severe than past ones.
