Doctors and pharmacists will be brought into Victorian primary schools in a COVID-19 vaccination blitz for children aged five to 11, as hospitalisations reach an all-time high.

Premier Daniel Andrews on Tuesday announced a $4 million grants program for GPs and community pharmacists to establish mini-clinics at schools in areas that need more uptake.

Grants of up to $6500 will be available to cover staffing, travel and equipment, with an extra $5000 grant for schools to establish a vaccination clinic.

It comes a day after the age group became eligible for the jab, though some doctors reported supply issues and parents struggled to get bookings.

Mr Andrews flagged he would soon make an announcement on measures to ensure a safe return to schools at the end of January, which will be "consistent" with NSW.

Victoria recorded 37,994 new COVID-19 cases and 13 deaths on Tuesday, with hospitalisations increasing by 43 to 861, including 117 in ICU and 27 on ventilation.

It is the highest number of hospitalisations since the pandemic began, surpassing the peak of 851 in mid-October 2021 when the state was battling an outbreak of the Delta variant.

Despite higher daily case numbers during the latest outbreak, fewer people have required hospitalisation, largely due to the milder nature of the Omicron variant.

The government has already put a freeze on all but the most urgent elective surgeries, and several restrictions have been introduced to reduce pressure on the hospital system.

Modelling suggests infections will peak at the end of January to early February, with hospitalisations and deaths to peak in the subsequent weeks.

Mr Andrews said 3992 hospital staff and 442 Ambulance Victoria staff were unable to work on Monday because they have either contracted COVID-19 or are a close contact of a positive case.

"I expect that number is in fact higher, and that does put great pressure on our system," he said, in his first press conference for 2022, .

"It's not a matter of money or a matter of machines ... it's qualified staff, it's people who provide health care."

Ambulance Victoria overnight issued a code red alert as it was experiencing "extremely high demand for ambulances" in metropolitan Melbourne.

"It is likely there will be a delay in an ambulance reaching you," it said in a statement.

"Our priority is to provide care to Victorians who require life-saving assistance."

AV asked Victorians to only use triple zero for emergencies and to contact Nurse On Call or visit their GP if their illness is not an emergency.

The same alert was issued on January 5 and was attributed to a surge in COVID-related patients calling triple zero for non-urgent care, including those asking where they could get rapid antigen tests.

Meanwhile, the Department of Transport says there may be disruptions to services over the next few days because many staff are isolating.

The number of people using public transport is currently 29 per cent of pre-COVID levels.

Under new pandemic orders that kick in at 11.59pm on Wednesday, the state will mandate vaccine boosters for critical workers, indoor dancefloors will close and food workers will be exempt from isolation rules.