A 16-year-old is in intensive care after an illegal 16th birthday party sparked a virus outbreak in Victoria, prompting a Melbourne school to warn parents about breaching COVID-19 restrictions.

Parents at St Columba’s College in Essendon, in Melbourne’s north-west, were sent a letter to remind families of social gathering dangers after several students caught the virus at the event.

The teenager is one of 564 virus patients in Victorian hospitals – a rise of 39 on Wednesday. There are 115 people in the state’s ICUs with COVID, including 74 on ventilators.

Victoria had 1638 more local cases and two deaths on Thursday, taking the toll from its current outbreak to 70.

Premier Daniel Andrews said the state’s case numbers were “higher than we’d like them to be”.

Private gatherings such as parties are banned under Melbourne’s lockdown rules. In the letter to parents, St Columba’s College principal Rita Grima, wrote “a number of people” at the 16th birthday party had since tested positive to the virus, including the teenager in ICU.

“A gathering of the nature that has been described to me is not currently permitted,” she wrote.

The event reportedly involved year 10 students from St Columba’s and two other local schools.

Melbourne radio network 3AW published the letter.

Tweet from @VicGovDH

Thursday’s tally is the eighth consecutive day of more than 1100 cases in Victoria, while active infections pushed past 15,000.

It is Victoria’s second-highest daily case tally in its Delta outbreak.

Despite that, Mr Andrews said on Thursday he had no plans to alter Victoria’s roadmap out of lockdown, despite new NSW Premier Dominic Perrottet accelerating his state’s reopening after it reached the 70 per cent double-dose milestone on Wednesday.

Victoria is expected to reach that milestone on October 26.

“Other states can make their own decisions. The most important thing for us to do is to continue to see that first and second dose rate tick up,” Mr Andrews said.

State acting chief health officer Ben Cowie said on Thursday he was concerned about Victorians’ immediate access to immunity amid concerns of future booster shots because of the state’s rising cases.

Ben Cowie said Victoria was facing record high case numbers. Photo: AAP

The Burnet Institute modelling behind Victoria’s roadmap projects a seven-day average of up to 2900 cases by mid to late-October.

Corresponding peaks in hospital and ICU demand could reach as high as 2500.

“We are facing the highest case numbers we’ve ever done in Victoria, we are facing increasing numbers of people ending up in hospital,” Professor Cowie said.

He said in the seven days from Tuesday last week to Tuesday this week, Victoria had about 10,000 virus cases. Of those, 7 per cent of people were fully vaccinated, 15 per cent had had one dose, and 79 per cent were unvaccinated.

More than 77,000 Victorians were tested for the virus in the 24 hours to Thursday morning, which is another record. At state-run vaccine sites, 36,672 doses were administered.

Meanwhile, Professor Cowie said abattoirs and meatworks remained an industry of concern across the state, with 10 worksites identified as exposure sites in the past week. There are more than 30 confirmed active cases associated with these sites.

The Victorian government also announced plans to establish 10 dedicated COVID vaccination pop-up hubs in hotspots to boost coverage among people with disabilities.

The state government has pledged $5 million to launch the pop-ups across October, which will allow disabled residents to come forward to get the jab without a booking.

Ageing and Disability Minister Luke Donnellan said more than 71 per cent of Victorian NDIS participants aged 16 and over had received their first dose as of September 30.

That compares to 84.4 per cent of the state’s general population.

“We need to keep pushing,” Mr Donnellan said.

“It’s just not acceptable where it is at the moment. We can’t open up when we’ve got people living with disabilities, with vulnerabilities, if they’re not at a higher rate of vaccinations.”

– with AAP