Warrnambool is sitting at 79.8 per cent for second doses, right on the cusp of the ultimate roadmap target of 80 per cent double dosed, with Southern Grampians, Corangamite and Moyne close behind.

In the vaccine race for regional Victorian cities, Warrnambool took an early lead and hasn't been headed, with a leading epidemiologist saying the city's vaccination rates played a key role in controlling its recent outbreak.

The numbers are extraordinary, but are they too good to be true?

The government stops updating the vaccination rate figures once an area hits 95 per cent. That is because it wants to avoid the embarrassing situation where an area goes beyond 100 per cent coverage, which is statistically impossible.

The vaccination rates published by the federal government are calculated by dividing the number of people receiving a dose by population figures from the Australian Bureau of Statistics.

The ABS population data used in the vaccination stats is an estimate from 2019 updating the official 2016 Census figures. But since 2019 the regional Victorian population has grown by at least 20,000 people, a trend supercharged by the COVID-19-inspired exodus from major cities like Melbourne.

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According to statisticians at the ABS like Andrew Howe, more people have been settling in regional Victoria, and fewer people have been moving to the big smoke.

It means the regional population figures being used in the vaccination data are likely to be underestimates. That would artificially boost the vaccination rates being calculated.

Without accurate Census data it is impossible to know how much the rates are off by. But the message from leading epidemiologists Professors Catherine Bennett and Tony Blakely is for the south-west to not rest on its laurels.

"Numbers are good, but you shouldn't obsess over them. We just have to get as many people vaccinated as possible," said Professor Bennett.

"Seventy per cent is good, 80 is better, 90 is even better. There isn't just one target that we want to hit and then stop," said Professor Blakely.

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