Of the 176 new cases on Thursday, 67 were located in the northern suburbs of Melbourne, 61 in the west, 22 in the east and south, and 13 in the regional town of Shepparton.
“This virus is here, right now, and it is spreading fast,” Acting Chief Health Officer Ben Cowie told reporters.
“The increasing case numbers are a herald of what our health system is going to be faced with in the coming weeks and months.”
More than 3000 people were swabbed as part of day 13 testing in Shepparton on Thursday, which could further lift case numbers on Friday.
Health Minister Martin Foley said Burnet Institute research had suggested the state’s lockdown had avoided a further 6000 cases in the past month, but now was the time to pivot.
“You’ve got to follow the advice of the science. Delta has changed the script,” he said.
To aid Victoria’s quest to ramp up vaccinations, the interval between doses of the AstraZeneca COVID-19 vaccine has been halved to six weeks.
The move, effective immediately, makes the wait time between AstraZeneca doses the same as for Pfizer and will help the state reach its 80 per cent double dose target faster.
While clinical trials have shown AstraZeneca is most effective with a 12-week second dose interval, Prof Cowie said the state needed to strike a balance between long-term efficacy and increasing protection against the Delta variant.
The Victoria government late on Thursday announced a tightening of border restrictions, including a ban on crossing to use physical recreation facilities.
The number of communities in the border bubble has also been reduced with Greater Bendigo, Greater Shepparton, City of Benalla, Buloke, Loddon, Yarriambiack and two NSW LGAs, Broken Hill and Edward River, no longer defined as cross border communities.
The Specified Worker List has also been reduced and testing obligations for those entering on a Specified Worker Permit have been extended.