As Victorians prepare for a second week of extended lockdown, many have asked in frustration: “Why Victoria? What are we doing wrong?”

New South Wales seems able to control its coronavirus clusters while largely staying open, but Victoria has been forced to enter its fourth statewide lockdown – more than any other state or territory.

• Read: Frydenberg to ‘consider’ Vic lockdown support amid further pleas

Is it Melbourne’s demography?

Some top health experts have blamed demographic differences between Melbourne and Sydney as contributing factors.

Professor Marylouise McLaws, an infectious diseases expert at the University of New South Wales and member of the WHO’s COVID-19 response team, is one of them.

Speaking to the ABC on Monday, she pointed to some key features that she believes set Melbourne apart from Sydney.

• “Your city has younger people than Sydney has, and they like to go out,” she said. The theory goes that young people are generally very socially active, so they’re more likely to catch and transmit the virus
• Melbourne also has a “very well-connected migrant group”, where big families tend to live together under one roof. These close living conditions mean they could potentially pass on the virus to each other more easily.

But Dr Liz Allen, a demographer at the Australian National University, said the data simply doesn’t stack up.

“It’s simply not true to say demography and behaviour accounts for the different COVID experiences of Australia’s two most populous states,” she told The New Daily. 

“Victoria is very much like New South Wales across a range of relevant indicators.”

For example, she said, Victorians aren’t younger than NSW residents, nor are they more ethnically diverse.

In 2016, the population of people born overseas was roughly the same in Victoria and NSW – about 30 per cent, according to the Australian Bureau of Statistics.

“The trouble with pointing the finger at subpopulations here is that individuals are being blamed incorrectly, and as a result, face demonisation,” Dr Allen said.

Is it Melbourne’s transport habits?

Speaking to ABC Radio National on Wednesday morning, Labor’s aged care spokeswoman Clare O’Neil blamed Melbourne’s geography and transport use.

“The layout of the city is one where people move around a lot more than they do in Sydney, where people tend to stay within their suburbs,” she said. 

Professor McLaws also pointed out that Melbourne has “really great public transport”, which enables people to travel further – and potentially take the virus with them.

However, Dr Allen said if anything, data shows Victorians are more likely than NSW residents to jump in their car over taking public transport.

Sydneysiders have the highest rate of public transport use in Australia, ABS data shows.

Is it Melbourne’s population?

Not necessarily.

Housing isn’t more densely populated in Melbourne, nor do people there do more travel, Dr Allen said.

“In theory, population characteristics are important considerations in virus and disease outbreaks,” she said.

“But that’s not what’s happening here.”

Is this particular strain of the virus more transmittable?

“As time goes by, these new variants become more and more contagious,” Dr Norman Swan told ABC radio.

He said Victoria’s crisis was unlike previous outbreaks because it was spreading through “fleeting contact”, sometimes among strangers.

“You can’t compare what’s going on this year to last year. It’s a different circumstance,” he told the program.

“What it is, is bad luck and what NSW had three or four weeks ago was good luck.”

So if it’s not age, population or transport habits, then what is it?

“Luck plays a role,” Dr Allen said.

“But leadership and public health measures matter, too.”