Warrnambool's high vaccination rate helped stop COVID-19 outbreak, expert says

Just one week ago the city recorded 12 new daily cases, easily its highest figure of the pandemic, setting residents and health authorities on edge, but the numbers have subsided with the past two days featuring no new cases in Warrnambool.

Deakin University chair of epidemiology Catherine Bennett told The Standard Warrnambool's success was largely due to its highly vaccinated population.

"Being at a high vaccination rate makes a big difference in an outbreak," she said.

"That's not just the double dose rate, but the first dose too."

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Warrnambool and the south-west has consistently led the state for first COVID-19 vaccine dose rates. The region hit 91.5 per cent in the latest data, with Warrnambool itself even higher at 94.2 per cent.

"Your risk of needing to go to hospital decreases by two thirds when you have one dose of the vaccine, and with two doses it decreases by 95 per cent," Professor Bennett said.

The regional rate for second doses reached 62.2 per cent at last count, with Warrnambool at 65.3, perhaps only a week away from hitting the 70 per cent mark.

The Warrnambool outbreak was seeded when a woman returned to the city after testing positive in Melbourne. Several members of her household caught the virus and passed it to three other households.

That was why Warrnambool's case numbers spiked from four to 12 overnight. Professor Bennett said it was a common pattern with the Delta COVID-19 variant.

"You always get a jump in cases because of the household transmission," she said.

Professor Bennett said the virus also usually managed to seek out unvaccinated households.

"I haven't seen the data, but if they found it just within those specific households they were probably less vaccinated."

She said the ability of local health authorities to stop further household-to-household transmission was largely thanks to vaccination.

"When only 5 per cent of the population in Warrnambool is totally unvaccinated it is much easier to manage and you don't really have to worry about the hospital getting overrun," she said.

But Professor Bennett cautioned against complacency, saying vaccination was only part of the success story. She said the vigilance and high testing numbers also played a significant role and Warrnambool residents needed to keep their guard up.

"It takes about two to three weeks before you know for sure whether there is something still out there that will come back to haunt you," she said.

"It's great to see Warrnmabool hasn't become complacent and people are still getting tested. Really you've got the best of both worlds with a highly vaccinated population and a community that takes the outbreak seriously."

There is mounting evidence of the Delta variant being much easier to control in regional areas, with outbreaks in regional Victorian cities being regularly stifled in recent months.

"There are a whole lot of things that make it easier to control in regional areas," Professor Bennett said.

"The lower density means less household-to household transmission, which is what really spreads the virus, but it's also easier to see what's happening at the beginning of an outbreak. Then there is the high vaccination rates."

Many in and around Warrnambool were concerned the area would be plunged into lockdown after cases spiked last week. Professor Bennett said the area's high vaccination rate would have prompted a wait and see approach from the Department of Health.

She said the city's experience is a good primer for what "living with the virus" is likely to look like.

"Watching Warrnambool control its outbreak is a sign of the future," she said.

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