University of Auckland student Dr Esther Willing has been studying health targets for immunising two-year-olds as an example of closing stubborn gaps between Māori and non-Māori.
The government target to increase overall immunisation rates among two-year-olds ended in 2012, and led to a rise in the Māori immunisation rate from 67 to 91 percent.
Dr Willing said the rate finished only 1 percent behind the non-Māori rate, effectively closing a gap which had existed for over 10 years.
"Because there were such big inequities between Māori and non-Māori at the start, those gains that were made by Māori were really big.
"I found that really interesting, because the health target says nothing about improving outcomes for Māori but, as policy, it was actually able to address the inequities that were there for Māori children."
Māori generally have poorer health than other ethnicities in New Zealand.
Māori-specific strategies could be met with resistance from the public, Dr Willing said.
But the national immunisation target meant the health sector was committed to the same goal, and improved their systems to get the job done.
"We know that there are many barriers to accessing primary care for Māori within New Zealand, and so by addressing some of these barriers, they're improving the systems and processes, and DHBs (district health boards) were able to improve immunisation coverage for Māori children.
"It shows that we could actually address health inequities in some areas by focusing on improving the systems and processes within the health system itself."
About half of the babies born in Hawke's Bay are Māori, and its DHB now has higher immunisation rates for Māori than non-Māori.
Hawke's Bay DHB director of population health Dr Caroline McElnay said that was because it strengthened its approach years before the national health target came in.
"We took a very systems approach to the problem and said if we can get the system working for everyone, it will work for Māori as well as for non-Māori."
The focus had been on getting systems and training right, especially with frontline staff who engaged with families at every stage, she said.
Immunisation Advisory Centre director Dr Nikki Turner said a systematic approach could reduce other health gaps between Māori and non-Māori.
It worked for immunisations because everyone was behind the targets but just setting a health target in isolation would not yield the same results, she said.
"It has to be set within a systematic approach to delivering it, which includes being able to measure, being able to feed back and, really importantly, being able to absolutely support the frontline staff to deliver well and to feel supported."
Dr Turner sits on the World Health Organisation International Committee.
New Zealand's move to set immunisation targets was being considered internationally, she said.