There has been a fresh warning about how dangerously low immunisation rates could lead to a measles outbreak.
A new study by the University of Otago has found not enough children under the age of five in New Zealand are protected against measles to stop a potential national outbreak.
This is because the number of children receiving the first measles, mumps and rubella (MMR) vaccine is declining.
The first MMR vaccine (MMR1) decreased from 95.1 percent for children born in 2017 to 88.9 percent for those born in 2020.
The second MMR vaccine (MMR2) was below 90 percent for all years examined, the lowest percentage being 61.6 percent for children born in 2018.
Lead author Dr Nienke Hagedoorn, of the Department of Paediatrics, said that percentage of immunisation coverage was insufficient to prevent community transmission in children under five.
More than 95 percent coverage for the first vaccine is required.
"This is important because young people who are unvaccinated are at high-risk for measles-related complications, such as hospital admissions or even death," said Dr Hagedoorn.
During the year examined the district health boards in Bay of Plenty, Lakes, Northland, Tai Rāwhiti, West Coast and Whanganui all reported less than 90 percent vaccination for MMR1.
The study also found that MMR1 coverage was lowest for children of Māori ethnicity, and this declined over time from 92.8 percent for those born in 2017 to 78.4 percent for those born in 2020.
Dr Hagedoorn said nationwide catch-up immunisation programmes were urgently needed to improve immunisation coverage and prevent an outbreak.
The last outbreak in New Zealand was in 2019, which then spread to Samoa.
"Since the borders in New Zealand have fully opened and the number of measles cases around the world has increased, the chances of measles being imported into New Zealand have also gone up," she said.
It was important parents knew the vaccine was free to get, safe and will protect a person for their whole life, she said.