The defence force and reinforcements from other states have been called in to help Victoria’s efforts to contain coronavirus cases.

The state called in the Australian Defence Force and experts from NSW, SA, Tasmania and Queensland on Wednesday after recording 20 more infections and a death.

“This support will mean we can get even more tests done and results back quickly – and a stronger effort to remind Victorians if you are sick, stay home and get tested,” a government spokeswoman said.

About 300 troops are likely to be deployed in Melbourne to help manage quarantine hotels, from where the virus has been spreading from travellers to security guards to their wider families. Of the state’s more than 150 active cases, more than 30 are linked to hotel staff or their close contacts.

Victoria’s 20 virus infections on Wednesday, all in Melbourne, marked the state’s eighth day in a row of double-digit COVID rises.

Chief health officer Brett Sutton also confirmed the death of a man in his 80s overnight. He is the state’s 20th coronavirus fatality, and Australia’s 103rd – and the country’s first COVID-19 death since May 23.

It came as supermarkets slapped purchase limits on toilet paper and hand sanitiser amid “significantly elevated demand” in Victorian stores.

Community engagement in the municipalities of Brimbank, Casey, Cardinia, Darebin, Hume and Moreland has been ramped up, including doorknocking, after they were identified as coronavirus hotspots.

The areas have large migrant populations, with many speaking languages other than English at home.

Professor Brett Sutton said engaging with linguistically diverse communities wasn’t as simple as handing out translated pamphlets.

“You do need that community leadership, community champions and all of the modes and methods available to you,” he said.

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Federal Health Minister Greg Hunt said the government has held almost 4500 consultations with migrant and community leaders.

He blamed Australia’s Black Lives Matter protests two weeks ago for a “relaxation” of attitudes towards social distancing.

“Many Australians have said, ‘Gosh, if it’s OK for 10,000 people to congregate and huddle together, surely it would be OK for 10 in my family’,” he said.

Victorian authorities have been consistent in their message that the recent outbreak is driven largely by families getting together without following proper physical distance and hygiene rules.

There have been four positive COVID tests linked to Melbourne’s BLM march on June 6 – and none in other states where there were also protests.

Of Wednesday’s new Victorian cases, three are linked to a Keilor Downs family cluster, three work at Hampstead Dental in Maidstone, and another case has been linked to St Monica’s college at Epping.

One case has been linked to Northland H&M, bringing the total number of infections there to five.

Professor Sutton said 241 cases had been identified as community transmission, an increase of eight since Tuesday.

The reproduction rate of the virus has also increased, with those infected passing it on to an average of 2.5 people.

“When it’s at two, it means the active cases we have are doubling with each generation,” Professor Sutton said.

“We have seen the community transmission figures go from single figures [of cases] to above 10. So it’s no surprise the REFF is at two or above.

“But with the stabilisation in numbers in the last two days, I expect that that will go back down and I absolutely hope that we can get it below one and drive those numbers back down to zero.”

The last peak in the state’s reproduction number was in March, when it was closer to three – before mass gatherings were put on hold and mandatory hotel quarantine was introduced for Australians returning from overseas.

“We had an opportunity to drive numbers down. We still have that opportunity if people can isolate, test and have contact tracing,” Professor Sutton said on Wednesday.

Outbreaks from hotel quarantine are another concern in Victoria.

Since the spike in new cases, drive-through testing sites have experienced extremely high demand, with four-hour waits at some sites and people turned away at others.

“Demand has spiked incredibly, not unsurprisingly, but I guess, you know, we need to be mindful of that ongoing demand. We want to be able to meet it,” Professor Sutton said.

He urged Victorians to try other testing sites, and to book tests through GPs, before going to drive-in sites.

• Find information on Victoria’s COVID-19 test sites here

-with AAP