Covid 19 coronavirus: Hundreds forced into isolation as another coronavirus case confirmed at Melbourne school

There are 10 mystery cases in Melbourne - and zero in regional Victoria.

Hundreds are in isolation as another contact at a Melbourne school tested positive for COVID-19, sparking concern about easing restrictions.

Nearly 1000 people have been forced into isolation across Melbourne's northern suburbs after a school student tested positive for coronavirus.

Department of Health and Human Services testing commander Jeroen Weinmar said 83 families associated with East Preston Islamic College were now limited to their homes.

He urged any family who had a child at the school to come forward for testing on Friday.

Friday's only new infection was a parent from the Preston school.

"That will in turn generate more close contacts and more secondary contacts.

Around 400 people are secondary contacts of the cases at the East Preston Islamic College," Weinmar told reporters today.

"We also have an additional 390 secondary contacts of the ongoing work spread across quite a large number of suburbs in the northern area. That makes around 800 people who we are asking to self-isolate.

"What we saw yesterday at Broadmeadows and what we've seen at Shepparton and what we've seen at Kilmore is the importance of going wide quickly, of testing as many people as possible and then trying to focus on any remaining cases that we have."

Weinmar assured the new positive case, "based on our initial conversations with her", had had "very few contacts" outside of the house.

There were no further deaths on Friday as Melbourne's 14-day rolling average fell from 6.1 to 5.5.

There are 10 mystery cases in Melbourne – and zero in regional Victoria.

Regional Victoria has a daily case average of just 0.3.