Health authorities are concerned about a sharp drop in vaccination rates in Northland, particularly as fewer babies from poor and Māori families are immunised against serious diseases.
Ministry of Health data and documents show while great gains in infant immunisation rates in New Zealand were made between 2009 and 2016, since early 2017 rates have started to decrease.
"This decrease is primarily driven by a reduction in Māori immunisation rates with a resulting widening of the equity gap in infant immunisation coverage," it said.
Māori immunisation rates are of greatest concern in the Northern region, which includes Northland, Auckland and Counties Manukau.
In Northland, total rates fell 5.7 percentage points to 64.2 per cent vaccinated as at March 2019.
Northland Māori immunisation rates dropped 12 percentage points to 53.4 per cent vaccinated, while rates for the most deprived in the region dropped 9.6 percentage points to 58 per cent.
While Northland Asian rates increased 21 percentage points to 93.3 per cent, Northland European rates fell 2.4 percentage points to 76 per cent.
The figures follow a nationwide trend, where just 77 per cent of 6-month-olds in New Zealand are now getting their vaccines on time, down 4.5 percentage points since rates peaked in 2016.
Coverage of at least 90 per cent is needed for herd immunity. Anything below this puts children at risk of vaccine-preventable diseases, particularly whooping cough and measles.
Northland District Health Board Medical Officer of Health Dr Catherine Jackson said immunisation coverage is closely monitored to identify trends.
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There are multiple strategies across Northland focusing on achieving equitable outcomes for Northland children including public health nurses offering vaccinations at homes and at B4 school clinics.
But it "is concerning" that at 6 months of age Māori babies are less likely to be fully immunised than non-Māori babies, she said.
Being fully immunised by 6 months of age is challenging for many families, however most children are fully immunised by 2 years of age, she said.
"Many people have different health beliefs, including about immunisation. Vaccine hesitancy occurs in all populations around the world, despite overwhelming evidence that immunisations are safe and effective. Family life is becoming increasingly busy and complex, which makes it hard for some families to access preventive healthcare including immunisation."
The Health Ministry said it recognised an "urgent need" to address the decrease in vaccination rates, particularly among Māori.
In March it launched a campaign aimed at Māori and Pacific families, and two months later identified seven possible reasons Māori families were not vaccinating - including socioeconomic barriers; a lack of flexibility with the general practice model; greater workload for outreach services; and vaccine hesitancy.
"The barriers to immunisation are complex and multifactorial ... and are likely part of a larger picture indicating a growing systemic issue with inequity in health services," it said.
Kerikeri GP Dr Simon Bristow, who is based at KeriMed, said he experiences more issues with anti-vaxxers, including people from overseas and Kerikeri residents, at his practice.
In his experience Māori patients are receptive and happy to take up immunisations for their children, he said.
"It relates more to health inequalities with Māori not accessing healthcare services, not getting to clinics, and also living in rural areas," Bristow said.
"It's just getting the education and information to the population, so they understand the reasoning.
"Health literacy is being able to understand why you need to get it done and accessing services which has been a stumbling block.
"That's the main thrust of the PHOs and DHB, to try to correct inequalities in Northland that have been there for many years."
The Northland-wide health entity, Mahitahi Hauora formed in July by merging Whangarei, Kaipara, and Te Tai Tokerau PHOs in a bid to close the health equity gap for Māori, have better co-operation between health and social services, and more training for rural GPs in Northland.
Chief executive Phillip Balmer said immunisation rates are closely monitored by his team, and the 6-month coverage rate for Māori babies "is concerning".
However, coverage rates for Māori babies at 8 months is 80 per cent, which is pleasing, he said.
"Access to services, beliefs, and awareness are some of the factors involved in decision-making about immunisation.
"We work to increase awareness amongst parents and whanau about the importance of protecting your children. We encourage parents and caregivers to have babies immunised on time."
Both Mahitahi Hauora and NDHB strongly recommend pregnant women are immunised for whooping cough as well as influenza as immunity is passed onto the baby.
Jackson said as vaccine-preventable diseases become less commonplace because of immunisation people become less aware of how serious these illnesses can be.
For example, although measles is thought to be a mild childhood illness, five of the 22 people with measles in Northland this year were hospitalised, including two people who needed intensive care treatment.
Children can be immunised for free at a drop-in clinic run by the NDHB at the Well Child Hub in Commercial St Whangarei on Thursdays from 8am to 4.30pm.
'It was touch and go'
Being a practice nurse, Crystal Lui always knew the importance of getting children vaccinated on time.
So the Kaikohe mum never hesitated to have any of her five babies immunised.
But nothing prepared her for the time her fourth baby contracted whooping cough at just 2 weeks old, before she'd had a chance to get her shots.
"It was quite scary; she was very unwell," Lui said.
"She ended up in hospital and was there for several days. She was having trouble breathing and had a barking cough and was put on oxygen. I was really quite scared for her. It was touch and go."
Lui's children are now aged 14, 11, 10 and 7 years, and 18 months.
She graduated from her bachelor's degree in nursing at NorthTec in Whangarei in December 2018 and has been working as a practice nurse at Broadway Health in Kaikohe since March 2018.
She's had all her babies immunised on time, at 6 weeks, and "highly recommends" parents and caregivers get their children vaccinated.
"My kids have never really been unwell, because they've all been immunised on time.
"Even when I was pregnant with my last baby, I had the flu vaccination and meningococcal vaccine which helped protect him. He's never been unwell."
The National Immunisation Schedule is a series of vaccines that are offered free to babies, children, adolescents and adults.
Northland District Health Board recommends pregnant women are immunised for whooping cough as well as influenza.
Medical Officer of Health Dr Catherine Jackson said being immunised during pregnancy and on time at six weeks, three months, and five months is the best way to protect very young babies.
The Ministry of Health has recently expanded eligibility for whooping cough vaccine in pregnancy so it can be given from the second trimester of pregnancy onwards.
Immunisations are provided at all primary care practices and are one of the most important services they provide.