Victoria has recorded one new community case of COVID-19, which is likely connected to the larger Kappa strain outbreak responsible for Melbourne's recent two-week lockdown.
For now though, it remains a "mystery case", testing commander Jeroen Weimar said on Saturday.
The case, a young father who lives in central Melbourne, did everything right, Mr Weimar said, getting tested as soon as he noticed symptoms.
His three family members were tested on Saturday morning and are awaiting results.
Mr Weimar said low testing numbers over the past several days continued to be a major concern because authorities believe there are "other branches (of infection) out there that are not yet discovered".
"We need to make sure we run this to ground now. We do not want to go through this (lockdown) again," he said.
Mr Weimar encouraged Victorians to call each other out if they notice a friend, colleague or hospitality worker exhibiting COVID-19 symptons.
"Call them out in the nicest possible way. Ask them have they had a test," he said.
Health authorities added 19 new exposure sites to the state's list on Friday, mostly linked to a Reservoir case detected a couple of days ago.
Summer Hill Medical Centre in Plenty Road, Reservoir is listed as a "tier 1" site, meaning anyone present at that location on June 5 between 8.45 and 10.30am must get tested and quarantine for 14 days.
The rest of the new exposure sites are "tier 2", requiring immediate testing and isolation until a negative result is received.
These include a medical clinic, chemist and Coles Express in Taylor's Hill on March 31 and an electrical supplies wholesaler in Thomastown Rexel Aust for three full days on 19, 20 and 21 May.
There are now 74 active cases in the state, including returned travellers in hotel quarantine.
Three new cases were acquired overseas and in hotel quarantine on Saturday.
Just over 15,000 test results were received in the 24 hours to Friday and 20,660 vaccine doses were delivered.
Melbourne emerged from two weeks of lockdown on Friday, following a climb in local cases since late May.
Melburnians are now allowed to travel up to 25km from home and meet outside in groups of up to 10 people. Masks are required indoors and outdoors. Hospitality, retail and schools have reopened.
The latest outbreak spread through the local government area of Whittlesea, north of the city, and the seaside suburb of Port Melbourne, forcing Melbourne into a two-week "circuit breaker" lockdown.
There are still 2300 primary close contacts seeing out quarantine.
Separately, a west Melbourne family were infected with the highly infectious Delta strain and that also became a cluster during lockdown.
There are 764 primary close contacts to that cluster still quarantining.