Victorians who are double vaccinated need to pivot their thinking again, as the state grapples with more changes and a sub-variant of Omicron is detected.
"We're going through a bit of an uncertain time. We're adjusting our thinking that to be complete from a vaccine point of view ... we now need to have three doses," Victoria's Covid Commander Jeroen Weimar said on Saturday.
"Unfortunately the Covid pandemic continues to evolve and we need to evolve with it."
He said double vaccinated people were "not as protected" and people due for a booster need to "get it done now".
Authorities have detected "literally a handful" of cases of an Omicron sub-variant, dubbed son of Omicron.
"We're obviously following the international developments on the BA.2 sub-variant of Omicron closely," Mr Weimar said.
"It's still very early days in understanding exactly how that's moving around, I'm aware there's a very small number of cases that have been detected here in Victoria."
He stressed son of Omicron was not a new variant of Covid-19.
The state's Covid-19 hospitalisations fell by 35 on Saturday to 953 patients.
Of those, 114 were in intensive care and 39 were on a ventilator.
The state government has delivered 4.5 million rapid antigen tests to schools with another two million on the way.
Private school students returned to school on Friday, and public students begin term on Monday. All staff and students are being encouraged to take a test twice-weekly.
A vaccination blitz targeting children aged five to 11 has begun at 15 Victorian primary schools, with seven state-run vaccine hubs offering walk-up jabs for kids.
More than 37 percent of Victorians aged over 18 have received a Covid-19 vaccine booster, with 22,139 doses administered at state hubs on Friday.
