ACT chief health officer Dr Kerryn Coleman said public health restrictions would not eradicate transmission of the Delta variant, but could cut one-third of the transmission effect.

"I actually think what we're doing now with our combination of public health, our directions and our social measures in place, with the level of vaccination coverage that we have, is working very well to keep us at this steady level of cases," Dr Coleman said.

"I actually don't see there's any need to go any particular stronger or harder at this stage, because I think we are accepting that we are unlikely to get back to zero again."

The ACT reported 16 new cases of COVID-19 in the 24 hours to 8pm on Monday, including nine cases linked to known outbreaks or clusters.

Three of the new cases were in quarantine for their entire infectious period, while 10 COVID-19 patients were being treated in ACT hospitals. Two people were in ICU where they required ventilation; they were aged in their 40s and 50s.

One of the ACT's leading doctors has conceded so-called COVID-zero is unrealistic in the territory, because the Delta variant was particularly effective at "getting into the engine room of our cities".

But Canberra Hospital infectious diseases physician Nick Coatsworth also told a Senate inquiry into COVID-19 the territory was in a much stronger position to combat the virus than during its first wave.

"We had our run for as long as we could. I was glad that we had it for as long as we did ... [but] I think the time of zero COVID is, unfortunately, over," Dr Coatsworth, a former Commonwealth deputy chief medical officer, said.

But Dr Coatsworth stressed increasing vaccination rates, and "considerably better" treatments for COVID-19 symptoms, put the territory in a stronger position than last year.

Speaking at a daily COVID-19 press conference, Dr Coleman said the ACT was now focused on stopping the rapid escalation of COVID-19 cases.

"Next week, at that [lockdown] checkpoint ... there'll be an opportunity for me to recalibrate and have a look at how much has our vaccination coverage gone up, how much additional suppression are we getting from our vaccination, what can we do while maintaining maximum public health settings. What can we do to ease off and give people a little bit more freedom and then progressively do that moving forward," she said.

Dr Coleman stressed the lower number of cases in recent days did not reveal a trend for the ACT outbreak and authorities still needed to wait and see what would happen.

"One number does not make a trend for us. This does apply as much for our low numbers as our high numbers. And this is particularly pertinent for a small jurisdiction," she said.

"While our numbers are definitely not small on our per capita, or per person, basis, they are small overall, and for that reason there is an increased degree of uncertainty about them."

Since August 12, there have been 641 cases of COVID-19 reported in the ACT, along with 10 introductions of the virus from outside the territory. There are 77 cases with no known links, up from 50 mystery cases a week ago.

Dr Coleman said two thirds of cases were household contacts, but essential workplaces - including childcare centres, restaurant kitchens, construction sites and rideshare vehicles - were where the bulk of community transmission happened.

The median age of cases is 26, while 189 people with COVID-19 have been aged under 18. People aged under 12 made up 17 per cent of cases.

READ MORE:

Health authorities have identified 27 clusters, with an average of 13 cases each, since the start of the outbreak. The average number of cases for each cluster had fallen which Dr Coleman said showed stay-at-home orders were working to reduce the spread of the virus.

Chief Minister Andrew Barr again defended the ACT's "pathway" from lockdown, saying the government had provided indicative dates of when restrictions were likely to change.

"I don't have the exact day and moment, but the end of this month and the middle of next will be two important times when we provide further information on the very detailed specifics in relation to, for example, activities, density quotients, reasons to leave home, those sorts of things," Mr Barr said.

The current lockdown is due to end on October 15, with a midpoint review expected next week.

Our coverage of the health and safety aspects of this outbreak of COVID-19 in the ACT and the lockdown is free for anyone to access. However, we depend on subscription revenue to support our journalism. If you are able, please subscribe here. If you are already a subscriber, thank you for your support. You can also sign up for our newsletters for regular updates.

Our journalists work hard to provide local, up-to-date news to the community. This is how you can continue to access our trusted content: