COVID would reach WAs regions within weeks of outbreak modelling shows

A COVID-19 outbreak in Western Australia would spread to the regions and vulnerable remote communities within weeks of the virus seeding in Perth, new modelling shows.

The scenario paints a bleak picture for rural areas with lower-than-average vaccination rates and could lead to some towns being shut off from the rest of the state to prevent regional hospitals being overwhelmed.

COVID-19 would not take long to reach Western Australia’s remote communities.

University of Western Australia mathematics professor Michael Small developed the modelling by analysing the connectivity between the city and the regions to determine how long it would take for an outbreak to reach certain areas.

While each town and remote community had slightly different results, Professor Small said the findings were “bad everywhere” â€" particularly in the North West.

“Given an outbreak starts in Perth on day zero, and that then persists in Perth and bubbles along much like Melbourne and Sydney â€" not getting out of control too much, but not being controlled either â€" typically the first 30 days is OK, but after 30 days you’ll see transmission in towns,” he said.

“We found that because there’s a lot of movement between remote communities and between remote communities and rural centres, although you have a large number of very small communities throughout the state, they almost act like a virtual town or virtual city in that they’re connected to one another.

“The grocery truck is driving around from one town to the next to the next, and people are quite mobile, for example, in the Kimberley everyone comes into Broome at the weekend for the footy.”

Professor Small said the modelling â€" based on the Delta variant â€" showed 70 per cent vaccination rates in the Doherty Institute’s National Plan were insufficient.

“Even at 80-90 per cent one still needs targeted control and mitigation,” he said.

“There is a path out of lockdown and travel restrictions, but we will still need to adhere to contact tracing and some measure of control on movement â€" particularly to remote and vulnerable communities.”

UWA’s modelling estimates when COVID would enter a community. The horizontal axis depicts a vaccination rate between 20 and 95%. The vertical axis depicts the likelihood of the virus arriving within a certain number of days. Credit:UWA

For example, the modelling showed that with a statewide vaccination rate of 50 per cent, Fitzroy Crossing â€" one of the state’s most remote towns â€" would likely have coronavirus cases in its community within 60 days.

At a vaccination rate of 80 per cent, the virus does not reach the town for an estimated 90 to 120 days.

WA Premier Mark McGowan has previously flagged regional areas and sub-sections of the community with lower than average vaccination rates may need to be closed off from the rest of the state when WA eventually reopens its borders.

Under his diversion from the National Plan for transitioning to living with COVID-19, Mr McGowan intends to wait until WA reaches a double-dose vaccination rate “above 80 per cent” and then open the borders around six to eight weeks after that point.

It’s predicted this will occur sometime between February and April.

In WA’s northern outback, 12.45 per cent of Indigenous people aged 15 and over are fully vaccinated, while Albany has 39.4 per cent fully vaccinated, and the Mid West has 33.8 per cent.

The figures are trailing the state’s overall vaccination rate of 41.48 per cent and the national rate of 46.67 per cent.

Professor Small’s modelling has been presented to the state government, and is expected to be strengthened in coming weeks, with mobile phone GPS data to be used to gain a better understanding of how West Australians travel.

UWA’s modelling estimates when COVID would enter a community. The horizontal axis depicts a vaccination rate between 20 and 95%. The vertical axis depicts the likelihood of the virus arriving within a certain number of days. Credit:UWA

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