Health Minister Martin Foley on Friday confirmed one of the parents and child stayed at the quarantine hotel after returning from overseas in early February.

The whole family began isolating at home on February 7, after it was revealed a staff member at the hotel contracted COVID-19.

"All have been quarantined at home during their infectious periods," Mr Foley told reporters.

He said "common sense would suggest" they haven't passed the virus on to anyone else.

A total of 22 cases have been traced back to another family of three staying on the third floor of the hotel at the same time, who contracted the highly-infectious UK strain of the virus overseas.

Authorities believe the outbreak began when one of the family members used a nebuliser medical device that caused the virus to spread through the air.

Fears the virus would spread into the community led to a five-day "circuit-breaker" lockdown, which ended on Thursday.

The state's COVID-19 Testing Commander Jeroen Weimar said more than 3500 close contacts linked to the Holiday Inn continue to self-isolate, including 88 returned travellers who stayed at the hotel.

"(The new cases) continue to build this picture of this super-spreader event on the third floor at the Holiday Inn," he said.

"We know that this particular family was also accommodated in one room on the third floor and it adds to that sort of that wider impact."

The new infections bring the total number of active cases in the state to 27.

Some 21,292 people were tested on Thursday.

It comes as Austin Health, Monash Health and Western Health hospitals have been chosen to distribute the state's first doses of the Pfizer vaccine.

Mr Foley said workers who are most likely to come into direct contact with people who could have coronavirus will be first in line for the jab.

This includes hotel quarantine workers, airport and port workers, high-risk frontline health staff and aged care staff and residents.

The vaccine will be administered at dedicated hospital facilities, in hotel quarantine settings, at Melbourne Airport and through mobile outreach teams.

The federal government has allocated 12,000 doses of the Pfizer vaccine to Victoria in the first week of the program.

About 59,000 doses are expected in the first four weeks.

Two doses of the Pzifer vaccine are required at least three weeks apart and it must be stored and transported at -70C.

Six other hospitals will also become vaccination hubs as more doses become available. They are Albury-Wodonga Health, Ballarat Health, Barwon Health, Bendigo Health, Goulburn Valley Health and Latrobe Health.

Mr Foley said the Barwon Health hub will begin its public sector residential aged care program next week, "trialling an outreach model to be implemented across regional Victoria".

Barwon Health will also vaccinate port of entry workers in Portland, in the state's southwest.

Meanwhile, viral virus fragments were found in the Boronia, Carrum Downs, Caulfield, Langwarrin, St Kilda East and Wantirna South sewage catchments this week.

Anyone in the area, as well as some neighbouring suburbs, with COVID-19 symptoms have been asked to get tested.

SUBURBS ON NOTICE AFTER COVID-19 DISCOVERY:

* Boronia and Wantirna from February 13 to 15, including parts of Bayswater, Ferntree Gully, Knoxfield and Tremont.

* Carrum Downs or Langwarrin from February 13 to 16, including parts of Skye.

* St Kilda East or Caulfield North from February 13 to 16, including parts of Balaclava, Caulfield and Elsternwick.

Australian Associated Press