All of Sunday's cases are linked to the state's current outbreaks and all were in quarantine throughout their infectious period.

But acting COVID-19 commander Naomi Bromley said people in a Richmond apartment building had been told to self-isolate for 14 days after being linked to a virus-positive case.

The stay home order affects around 20 residents at the building.

Health officials say Victoria administered 15,841 vaccine doses in the 24 hours to Saturday evening and processed 25,779 virus tests.

Sunday's numbers follow two cases reported on Saturday, one quarantined during their infectious period and the other a colleague of a Melbourne testing site worker at Moonee Valley Racecourse who was briefly in the community before isolating.

Health authorities were still investigating how the first Moonee Valley worker contracted the coronavirus.

Initial results from genomic testing have linked the case to the outbreak at Maribyrnong's Ariele apartment complex.

Meanwhile, Victoria - which now has more than one million fully vaccinated residents - has tweaked its Pfizer state clinic rollout.

As of Monday, all people who receive a first dose of Pfizer will wait six weeks - not three - for their second dose.

The delayed second dose is the same strategy being used in Greater Sydney to protect more of the population faster.

GP clinics run by the Commonwealth will continue to administer second Pfizer doses three weeks after the first dose.

Chief health officer Brett Sutton said Victoria was well placed to hit 70 and 80 per cent COVID-19 vaccination coverage, which would trigger escalating levels of freedom from restrictions nationwide.

"We're as well placed as any of the big states," Prof Sutton said.

"The best vaccine is the one that's available for you now if you're eligible ... clearly the risk has changed from ATAGI's point of view.

"What the situation is now in Victoria can change ... people can get protection now by getting a vaccine that's available for them."

Prof Sutton also said southeast Queensland had been declared a "red zone", meaning only Victorian residents can enter Victoria. They must then seek testing and quarantine for 14 days.

Southeast Queensland - including Gold Coast, Brisbane and Sunshine Coast - on Saturday entered a snap three-day lockdown.

Victoria is living under relaxed restrictions since coming out of its fifth lockdown last week, however private gatherings are not yet permitted and strict mask-wearing applies.

Australian Associated Press