There's been a big rise in the number of COVID cases in the ACT.
They've tripled over the last month, from 68 new cases in the last week of April to 242 new cases in the last week of May.
The spike has prompted Canberra hospitals to raise their alert level to "amber".
Businesses have also reported a rise in cases.
Under an amber alert, masks must be worn again in all public areas in hospitals and in other health facilities like clinics. Patients are restricted to two visitors at any one time.
People have also been urged to keep away from health facilities if they have cold or flu symptoms.
On Tuesday, there were 60 people in Canberra hospitals infected with the virus. A month ago, there were only 10. Four people died with COVID in the ACT in the last week of May.
North Canberra Hospital raised its alert level to amber last week and Canberra Hospital has just done the same. University of Canberra Hospital is also now on amber alert, as are all other Canberra Health Services facilities.
The level of alert rises when the strain on a hospital rises.
At the height of the pandemic, an amber alert was defined as between 15 and 30 per cent of beds occupied by a COVID patient, but since then the definition has changed so it depends on a variety of factors including cases out in the community.
Canberra Health Services said: "We are implementing additional safety measures to keep our staff, patients and their visitors safe".
The new measures were a precaution to make sure hospitals weren't overwhelmed.
"We will continue to closely monitor the situation to see if further changes are necessary to keep patients, staff and visitors safe," the spokesperson said.
Doctors warned that a rise in COVID cases was likely to become a regular part of the onset of winter as new variants of the COVID virus emerged (in the same way that the flu virus mutates each season).
"We would expect to see more respiratory virus activity in winter. Now, on top of that, there is a new subvariant, and it's got its own subvariants," Sanjaya Senanayake, an infectious diseases specialist at the ANU and Canberra Hospital, said.
"The reality is although the intense period of the pandemic is gone, COVID is here to stay. So instead of taking over, it's going to join with the other winter viruses every year," he said.
"Don't panic. These are respiratory illnesses that come up every year."
The new COVID type is known as the "FLiRT" variant, a descendant of the Omicron variant. Dr Senanayake said that its make-up could make it easier to catch, "although there's no evidence to show that it's more severe at this stage".
States such as South Australia have paused non-emergency surgery because of the COVID spike but Dr Senanayake said there had been no suggestion of doing that in the ACT.
But cases are rising across the country. "By all ways we measure COVID activity, there is an increase at the moment and this would be mostly due to the new subvariants," Paul Griffin, a microbiologist at the University of Queensland, said.
Businesses were also experiencing a rise in COVID cases, according to Greg Harford, chief executive of the Canberra Business Chamber.
This was compounding difficulties already caused by a shortage of staff in some parts of the Canberra economy.
The best advice is: "As the FLiRT variants are descended from Omicron, the current booster on offer in Australia is likely to offer substantial protection," Lara Herrero, an expert in infectious diseases at Griffith University, said.
"Although it's not guaranteed to stop you becoming infected, COVID vaccines continue to provide strong protection against severe disease. So if you're eligible, consider getting a booster to protect yourself this winter."
But, to put the current rise in perspective: A year ago, there were 946 new cases in the last week of May compared with the 242 in the last week of this year's May. But there is far less testing now so the comparison isn't reliable.
