"We're expanding the capacity of existing centres with more booths and our booking system is constantly, as more supply comes on board, being updated to accommodate new supply," he told reporters on Saturday.
"To further meet the increased demand that we're seeing from Victorians to come forward and get vaccinated, we will be establishing more drive-through sites, particularly in the north in the Wyndham area, in Melbourne's southeast and in the north in the Hume Whittlesea area."
Victoria administered 29,490 COVID vaccine doses in the 24 hours to Friday evening, a record, and conducted 33,675 tests for the virus during the same period.
Meanwhile, Melbourne's Chadstone shopping centre has been declared a tier two exposure site.
Anyone who visited the country's biggest mall between 4.26pm and 5.40pm on 7 August has been ordered to get tested and isolate until they receive a negative result. The Coles supermarket within the complex has also been listed.
There are now more than 450 exposure sites in Melbourne in total including Highpoint shopping centre and several large apartment blocks.
Of Saturday's reported 21 new infections, 15 are linked to a growing cluster in north suburban Glenroy, which has been driven by mystery cases in multiple households.
Of these, 10 have a connection to Glenroy West Primary School.
"What we have seen as a result of this growing number every day is that we have multiple outbreaks with multiple exposure sites, right across Melbourne," Mr Foley added.
"Whilst we have genomic links we still don't have a source of infections for a number of these positive cases."
Victoria' secretary of contact tracing Kate Matson said there were eight mystery cases in focus from the City of Melbourne, Glenroy, Melton South, Middle Park, West Brunswick and Wynham Vale, as well as those identified in Newport and West Footscray.
"We are very concerned about what we're seeing across Melbourne," she said.
"We won't have unlinked cases if people come forward to get testing as soon as they possibly can, at the earliest sign of symptoms."
Ms Matson said there were more than 14,000 primary close contacts across Victoria. Some 650 had been cleared over the past couple of days while the state's household engagement program had conducted a record 1277 visits on Friday.
Melbourne is in the second week of its sixth lockdown, brought on to contain several Delta variant outbreaks.