"This means we know how and where they became infected," ACT chief minister Andrew Barr told reporters in Canberra on Sunday.

Mr Barr said eight of the new cases were already in quarantine and the other five were infectious in the community.

The territory has now recorded 250 cases in the current outbreak, 20 of which have recovered. One person remains seriously ill in intensive care.

The ACT lockdown is due to end on September 2 but Mr Barr says there will need to be a staggered exit from restrictions.

He says he believes Canberra is on the path to quashing this outbreak.

"But we are still exposed to a new spark, another wave of the virus coming in to the ACT," he said.

"So whatever we do between now and when we get to the very, very high levels of vaccination that we need, we are going to have to be very careful and measured in our response."

He ruled out having different restrictions for different parts of the ACT depending on their rate of vaccination.

NSW, which surrounds the ACT, announced a record 1218 virus cases on Sunday and Mr Barr warned that that number may keep on growing, possibly reaching 2000 cases a day.

"Our hope, is that the NSW government's more immediate and clear regional lockdowns have a much greater dampening effect on viral spread on the basis that they got into it earlier," he said.

Around 64 per cent of Canberrans have had one coronavirus jab and just over 40 per cent have had two.

But Mr Barr believes it will require a continuous program of vaccination beyond hitting 70, 80 or even 95 per cent targets.

"All the evidence from the northern hemisphere suggests that the vaccines provide very effective protection but they do need to be boosted," he said.

"I think we can anticipate, if COVID follows the path of other infectious diseases, that it's with us for the rest of our lives and we will need to have a booster shot every year."

Australian Associated Press