A school in Melbourne's west has been forced to close with students and staff plunged into isolation after a teacher tested positive for COVID-19.

The Department of Health confirmed a new case of the virus in the community on Wednesday, after earlier reporting a day of no infections.

The case is a teacher at Al-Taqwa College in Truganina, forcing the school to close temporarily, the department said in a statement.

The teacher is currently isolating and being interviewed by contract tracers, with urgent investigations underway into how they contracted the virus.

All students and staff are being told to get tested and isolate until further notice, with transmission risks at the school being assessed.

In a letter to parents, obtained by radio station 3AW, the school said Thursday would be a student-free day with online classes resuming from Friday until further notice.

The school will remain closed for 14 days unless the department advises otherwise, the letter says.

The school was also a significant location for transmission in last year's second wave.

It comes as Coles in Yarraville has been listed as tier-two exposure site, the first in four days.

More exposure sites will be posted online soon, the department said.

EARLIER, 4pm:

Victoria has recorded a new coronavirus case after initially revelling in a day of no infections.

The Health Department on Wednesday afternoon said it was investigating a confirmed case and would provide more information shortly.

It comes a day after new federal government data showed vaccination rates in the Grampians remain on par with much of the nation.

New data released by the Federal government this week shows that only 19.2 per cent of people aged 15 and over in the Northwest region are fully vaccinated.

In comparison, both the Bendigo and Geelong regions have over 25 per cent of people aged 15 and over fully vaccinated, while six other areas have over 20 per cent.

However, 45.7 per cent have received at least one dose, ahead of parts of Melbourne and roughly comparable with Shepparton (46 per cent), Ballarat (48.1 per cent) and the Latrobe Valley in Gippsland (48.8 per cent).

IN OTHER NEWS

Earlier on Wednesday, authorities had warned Victorians will not get an early rules reprieve despite the state notching its first COVID-19 clean sheet since the fifth lockdown.

COVID-19 commander Jeroen Weimar said it was cause for quiet celebration and satisfaction.

"It's a symbolic marking of a point where there's no more COVID cases," he told reporters.

"It means we're on track with the strategy that we set three or four weeks ago."

But it has not inspired health officials to bring forward a review on restrictions and the current batch will remain in place until August 10.

"We still have active cases in our community right here that we know about ... we've still got just under 3000 primary close contacts ... and we still have ongoing risks in the rest of the eastern seaboard," he said.

Victoria's border bubble arrangements with NSW became stricter overnight on Tuesday.

Now, residents in the bubble can only cross the Murray River without a permit for six reasons: for necessary goods and services including for medical care and getting tested; care and compassionate reasons; paid or voluntary work; education; getting a COVID-19 vaccination; and for sport and exercise.

Mr Weimar said it was only a week ago that officials were caught off guard by an unlinked case of a Moonee Valley testing site traffic controller.

It remains unclear how the man caught the virus, but Mr Weimar said a review into the source of his infection would ramp up on Wednesday afternoon.

"There's a strong line of investigation around some movements that he had at work," he said.

Active cases are continuing to fall, down from 124 on Tuesday to 99. As is the number of exposure sites, dropping to 33 after soaring to over 400 at the peak of the outbreak.

More than 30,000 test results were received over the past 24 hours, while about 17,600 vaccine doses were administered at state-run sites.

There are nearly 60,000 vaccination bookings available in Victoria, including some 14,000 Pfizer appointments each week until early September after second dose wait times at state clinics were upped from three to six weeks.

Naomi Bromley, deputy secretary of COVID-19 vaccinations, also said the health department was looking at rolling out AstraZeneca shots at mass vaccination hubs for Australians under 60.

"We are actively considering that at the moment, and we think we'll have more to say on that in coming weeks," she said.

None of the nine COVID-19 patients hospitalised in Victoria were fully vaccinated. Two remain in intensive care, including one on a ventilator.

Meanwhile, the Victorian-NSW border bubble officially tightened for residents just before midnight on Wednesday, with all non-essential movement across state lines outlawed.

- with AAP

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