Victorian authorities are growing increasingly alarmed about the spread of COVID through Melbourne’s west.

Victoria has had 79 more local coronavirus infections on Friday, including 60 thought potentially to have been infectious in the community.

State Health Minister Martin Foley said interviews were ongoing with many of the latest cases, and the number who actually were isolation was expected to grow.

Initially, only 53 of the cases were associated with existing infections but by later on Friday another 10 had been linked.

Of more concern is the continued spread of the virus through Melbourne’s west and inner-west. There have been 150 cases reported in that area in recent days, including 46 on Friday – 12 from Wyndham in the outer-west and 11 in Newport, in the inner-west.

“We believe there are multiple chains of transmission and we’re looking at quite significant community transmission ongoing,” Victoria’s COVID-19 commander Jeroen Weimar said.

“Where I have concerns is the inner-west, ongoing grumbling transmission around Newport, Wyndham, that’s where we need to concentrate efforts.”

He confirmed many of the latest virus patients came from large households.

“That’s giving us a longer time period, more close contacts … and more risk,” he said.

In a trend widely seen in Sydney and during Victoria’s second wave last year, many of the recent out breaks are also linked to essential workplaces, which remain open during lockdown.

“The western suburbs is disproportionately a community that is full of essential workers and permitted workers,” Mr Foley said.

“They are out and about and there are other issues, about a very small number of some people, not just confined to the western suburbs, who do not follow the rules.”

Text messages were sent to many people in Melbourne’s west on Friday, requiring them to get COVID tests.

In a further worrying sign for authorities, a cluster of 94 cases linked to the MyCare childcare facility in Broadmeadows now has more than 1,200 primary close contacts in quarantine. It has also generated many exposure sites.

Among the new exposure sites added on Thursday is a Borgcraft food distribution centre in Altona and the Catch distribution centre in Truganina.

Mr Weimar said there were at least two positive cases linked to Borgcraft. Early investigations suggested transmission at or just outside work.

He said there were now “far higher levels of surveillance testing” in essential workplaces such as food distribution.

Testing has also been broadened generally across Melbourne’s west, with text messages alerting locals to potential virus exposure. There were long waits at at many local test sites on Friday.

Elsewhere, 10 of Friday’s cases were linked to the outbreak in the regional town of Shepparton. One is an aged-care worker from the Murray River town of Echuca, about 70 kilometres from Shepparton.

The fully vaccinated woman works at Wharparilla Lodge, a 92-bed home in Echuca. She last worked on August 20.

The facility has been locked down and a response is underway.

“Given the person involved had been fully vaccinated, and had PPE equipment on, was doing all the right things, given the high levels of vaccination of residents in the facility, we hope that the response will indicate one case and one case only,” Mr Foley said.

About 16,000 residents in the Shepparton region, which has a population of 65,000, remain in isolation. There are ongoing problems with the flow-on closure of food distributors, supermarkets and pharmacies in the central Victorian town.

Mr Weimar said 500 people connected to the Orrvale Primary School would soon be released from quarantine, after it was downgraded from a tier-one exposure site to tier-two.

He said the public health team was reviewing other exposure sites and would keep the community updated.

Victoria’s sixth lockdown is scheduled to end on September 2, but with a high number of mystery cases and people infectious in the community, it is expected to be extended.

“We will make all of those decisions based on the most up-to-date advice and at the moment, with another six days to go, it is too early to make that call,” Mr Foley said.

There are 660 active COVID-19 cases in Victoria. They include 37 hospital patients – 14 in intensive care, nine of whom are on ventilators.