All the new cases have been linked to existing cases. Only four of Canberra's active cases are under investigation, and work remains ongoing in finding the source of the outbreak in the ACT.

ACT chief health officer Dr Kerryn Coleman said the median age of people infected was 19.5.

The age of people infected ranged from three-years-old to 62-years-old.

"The median age is 19.5 years which gives us an indication that there are many, half of the number of cases that we have is under 20," Dr Coleman said.

There are 12,500 people in quarantine including 10,500 close contacts of COVID-19 cases.

Seven public venues have been identified as sites of transmission.

Four of the cases announced on Wednesday were linked to three schools: Lake Ginninderra College, Harrison School, and St Thomas Aquinas Primary School.

There are now 15 cases linked to Lyneham High School, 13 cases linked to Fiction nightclub, and Lennock Jaguar in Phillip has six cases associated with it.

Five cases are linked to Gold Creek School, and a further five are linked to Basketball ACT.

Two cases are linked to Assembly bar and three associated with the Downer Community Centre.

ACT chief health officer Kerryn Coleman said more young people were among the new cases and health staff would work with schools affected by the outbreak.

"We will continue to work closely with all schools and those in the community affected to make sure they have the support and information they need," Dr Coleman said.

All staff and residents at the Greenway Views retirement village have tested negative, following a positive swab from a staff member who worked at the Tuggeranong site while infectious.

Dr Coleman said the site would remain locked down for the full 14 days.

The list of exposure sites has swollen to more than 190, with five schools now implicated as close contact sites after positive cases were detected.

The strained health system has had about 6 per cent of the population, or 25,000 people, attend for a COVID-19 swab since lockdown began.

The outbreak is also taking its toll on the territory's health services. There are about 400 health care workers in the ACT who are in quarantine or isolation, which is impacting on services, including the closure of the inner north walk-in centrre.

Health Minister Rachael Stephen-Smith said the 400 staff in quarantine includes about 300 from Canberra Health Services and about 100 from Calvary Hospital.

Authorities have called on people retired from nursing and students to help the fight.

About 7500 people had self-identified as close contacts on Tuesday, a number which will continue to grow as the outbreak does.

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The ACT government says its looking to work with the Commonwealth on joint-funded programs to provide relief to many sectors, include commercial tenancies, tourism and private operated attractions.

Authorities added 10 more close-contact exposure sites to the list late on Tuesday night, with almost 2000 primary and secondary students at Harrison and their families to be sent into immediate quarantine.

St Thomas Aquinas Primary School in Charnwood and the Lake Ginninderra College canteen and gym were other education locations added to the growing list.

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