The ACT has stopped reporting vaccination rates above 99 percent to avoid confusion and anomalies when the official figure exceeds 100 percent in the coming days.
This figure is based on 2016 census data from the Australian Bureau of Statistics, before accounting for natural increases and changes in overseas migration.
But as the region moves towards full coverage, the inevitable slight inaccuracies in all estimates have made it more likely that its official rate will rise above 100 percent.
Commonwealth immunization rates were determined by comparing vaccines recorded in the Australian Immunization Register with Australian Bureau of Statistics 2019 population estimates.
The Commonwealth has stopped reporting certain percentages above the 95 percent threshold to avoid anomalies caused by delays in population data.
“These coverage rates may exceed 100 percent, as the ABS Estimated Resident Population does not receive real-time changes in population,” a spokesperson said.
They acknowledged that the inability to monitor real-time population changes can skew the figures, especially in certain age ranges, but said they were generally consistent in states and territories’ reports.
The ACT Treasury, issued in June, projected the area’s population at 431,826, which would leave only 4300 residents without a maximum first dose.
Commonwealth data showed that ACT first dose rates in all age groups 25 years and older exceeded 95 percent. But that figure has dropped to just 78 percent among 20-24-year-olds.
Prime Minister Andrew Barr on Wednesday downplayed the possibility of the ACT’s official rate exceeding 100 percent and said underestimating the population over 50 was dismissed by overestimating the 20 to 24 range.
“I think the two balance each other out, so our 98.5 [per cent] a real 98.5,” he said.
“It’s not a statistical oddity, because they estimate we have more college students right now than we actually have.”
ACT Health estimates NSW residents account for around 12 percent of vaccines administered in the region.
State and territory coverage figures are tied to a patient’s Medicare account, meaning those living in Queanbeyan but vaccinated in the ACT are added to the NSW count.
But using Medicare accounts was based on current addresses, which could pose certain problems among the more mobile young population.
Australian National University demographer Liz Allen said the ACT data reflects where vaccine recipients actually live. But he warned that comparing vaccines to population estimates comes with disadvantages, especially if they’re outdated.
“It’s not surprising that the government picks a data point and sticks to it: it prevents targets from constantly moving,” he said.
“[But] problem with a lock [population estimate] The basis for the introduction of the vaccine is that data in regions with large variation become potentially unacceptably inaccurate as we move away from the census.”
Dr Allen said the population of the area “has changed markedly” since COVID-19 began.
“Recently, thousands of people have left the area, especially overseas immigrants and international students who tend to be in their best working age,” he said.
First dose reservations in the ACT dwindled last month as there are no more people in the region needing the first vaccine. In the week beginning September 13, 15,561 first-dose reservations were made through the ACT’s mass vaccination clinics and practices at AIS. That dropped to just 3161 in the week starting Oct.
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