Researchers have delved into Covid-19 vaccine coverage by ethnicity, and have found that different ways of calculating the population size of each ethnic group (the “denominator”) unevenly affects vaccine rates.
This was raised as an issue throughout the roll-out, as the Ministry of Health relied on health service user (HSU) datasets – capturing those who engaged with the health system in the past year. These were known to be an undercount, and saw coverage among Asian populations top 100%.
Senior research fellow Dr Andrew Anglemyer; public health physician Dr Corina Grey; Associate Professor and Associate Dean Pacific, Sir Collin Tukuitonga; statistics academic Andrew Sporle; and public health physician and epidemiologist Dr Gerard Sonder compared 2018 census and HSU data.
* Covid-19: Close to one million eligible people have not got their booster yet, as Omicron looms
* Many children yet to be double-vaccinated against Covid-19
* Covid-19: Boosters or previous infection needed to prevent symptomatic Omicron – study
* ‘We go to where our community is’: A Pasifika health provider on the front line
Because HSU only captures people who use health services, younger and marginalised populations were likely underrepresented, leading to overestimates of coverage in these groups, they found.
However, using census data may underestimate subpopulation sizes of Pacific peoples, which could lead to underestimates of unvaccinated – highlighting the “difficulties” in using census data to estimate accurate subpopulation counts in “dynamic”, migrant populations.
Without accurate census estimates of groups under 25, comparisons between HSU and census data were also limited, they said.
Analysis showed the proportion of Māori aged 12 and over who were fully vaccinated (88.2%) was “significantly less” than those identifying as Pākehā/other (95.6%) and Pacific (96.5%).
Similarly, “significantly higher” proportions of eligible European/other individuals had been boosted compared to Māori and Pacific.
Public health physician Dr Tukuitonga said the findings overall affirmed what was already known: that Māori had lower vaccination coverage overall.
He said it was important going forward, particularly when you were looking at health delivery and coverage among Māori and Pacific populations, that both census and HSU data are considered together, to get a better picture.
“The different datasets did tell us that you have to be circumspect about the information we get. Especially as HSU data is so commonly used, you’re going to under-represent certain populations.”
University of Otago immunologist Dr Dianne Sika-Paotonu said it was “undeniable” that Covid-19 exacerbated pre-existing health inequities in health for vulnerable communities, including Māori and Pasifika.
Inequities in vaccination and booster uptake by ethnicity for both adults and children remain “clearly evident”, and continued vigilance and vaccination efforts are still needed in the face of Omicron, she said.
Māori and Pacific providers had worked “relentlessly and tirelessly” to help address inequities, reducing barriers to get people vaccinated, and this “hard work” needed to be supported to continue, she said.
What official data shows
Ministry of Health data as of Tuesday shows:
- 96.3% of eligible people aged 12+ have had their first dose
- 95.2% have had two doses
- 72.8% of the eligible 18+ population have been boosted
- 12.5% of eligible 16 to 17-year-olds (all ethnicities) have been boosted (6.1% of eligible Māori, and 7.2% of eligible Pacific teens)
- 91.3% of Māori over the age of 12 have had their first dose; 88.4% have had two doses and 55.9% of the 18+ Māori population are boosted
- 98.5% of Pacific peoples over the age of 12 have had their first dose; 96.8% have had two doses and 59.8% of 18+ Pasifika are boosted
- 54.7% of 5 to 11-year-olds have had their first dose, and 26.7% have had two doses
- 35.6% of Māori tamariki aged 5-11 have had their first dose, and 12.9% have had both
- 48.2% of Pacific children aged 5-11 have had their first dose, and 16.4% have had both.