One in 10 children in the Bay of Plenty didn't get vaccinated against dangerous diseases because their parents declined treatment.
It comes as Prime Minister Jacinda Ardern reveals New Zealand's frontline border workers will start to receive the first Covid-19 vaccinations next Saturday.
However, one doctor has concerns the decline rate in children would be much larger with adults as the Covid-19 vaccine becomes available.
The Ministry of Health data provides insight before the historic Covid-19 vaccine rollout - and related information campaign starting this month - because it shows how many families declined to give their child at least one core vaccination.
The figures don't include those not in contact with the health system - such as families not attending a GP practice, or those who didn't turn up at appointments or for whom no address or contact information is known.
The data records at least one vaccine decline among parents/caregivers whose child turned 2 between July 1 and September 30 last year.
Nationwide, this group was nearly 6 per cent but was much higher in the Bay with Lakes having the second-highest rate behind Northland at 10.3 per cent.
Meanwhile, the Bay of Plenty area measured third against other regions with a 9.7 per cent decline rate.
The lowest decline rate was in Auckland and Canterbury DHB boundaries (3 per cent).
The ministry said it doesn't record which parents may later consent to their children being vaccinated, and said a small number of declines could look like large percentages if they fell within a small population.
Bay of Plenty District Health Board planning and funding portfolio manager Tim Slow said without declines the board would meet "or be close to" meeting the Ministry of Health targets.
He said the region's vaccination rate had remained consistent over the past 18 months.
"The data reflects a consistent rate of decline in the Bay of Plenty from various community viewpoints; those opposed to vaccination, those sceptical of immunisation and those who are influenced at the time of scheduled vaccination by misinformation across the many channels of the media causing people to be fearful."
The data was known and a consistent challenge for the DHB's delivery models and teams, Slow said. As a way to combat the decline different approaches were used every time a new campaign was launched into the benefits of immunisation.
"We have continuously reviewed and improved our processes and are very aware where every 'due' baby is within the scheduled timeframe.
"Parents are able to exercise free choice around vaccinations and this results in a decline rate that has been consistent for many years."
From the public health perspective, Slow said he was confident in the coverage rate for herd immunity.
The current immunisation rate was concerning for Lakes DHB director of strategy planning and funding Karen Evison.
"More needs to be done to educate, encourage and support families and whānau to immunise their children.
"Any low rate of vaccination is a concern to Lakes DHB and should also be to our community," she said.
Local leaders needed to play a critical role in championing the importance of immunisation, Evison believed.
The majority of immunisations in Rotorua, Taupō and Turangi are carried out in primary care by GPs, however, the DHB contracts outreach services or immunise's "opportunistically" when a patient presents at the hospitals.
The Covid-19 pandemic had resulted in a low rate, Evison believed, as people feared for their wellbeing in the lockdown and did not visit health centres.
However, the pandemic should serve as a reminder of the importance of immunisation for protecting the wider Lakes population, Evison said.
From February 20, border and MIQ workers in Auckland will be offered the Pfizer/BioNTech Covid-19 vaccine.
Ardern said it would take roughly two to three weeks for all 12,000 frontline workers to receive the jab.
After that rollout is complete, their family members will be offered the vaccination.
A ministry spokesperson said planning for the largest vaccination programme in New Zealand's history "is continuing to work at pace", and a public information programme would start this month.
As well as the surveys, the ministry was using research papers and strategies from the World Health Organisation and OECD to inform this work.
"Our main focus is on providing clear, consistent access to trusted and transparent information."
Western Bay of Plenty Primary Health Organisation co-chairman Dr Luke Bradford said the decline rate was a shame and a risk to the community.
He believed the cause was multifactual, including misinformation through social media platforms, but was thankful there was herd immunity due to the rate of people who were immunised.
"Whereas obviously, what we need with the Covid vaccine is to really get those rates up so that we can achieve a herd immunity and hopefully protect our country and return our borders.
"But it might be worse [decline rate] with the parents."
Bradford understood different communities would have different drivers for declining a Covid-19 vaccine but said people might have to make a decision based on how they viewed their future.
"I think there will be some interesting, soft pressures on people that won't be spoken. Australia's already indicated with not coming in without a vaccine, so then people will have to make a decision about whether they want to go to see their relatives in Australia, go on their Gold Coast holiday because Australia is not going to let you in."
Waikato University professor Ross Lawrenson said while the data didn't count those who declined and then said yes after seeking more information, he believed more emphasis was needed on the importance of immunisation, especially as a Covid-19 vaccine was looming.
He said while herd immunity could be reached, it was unclear with new variants arising.
"What we don't know is how good the new vaccine or the vaccines are at providing herd immunity. It seems that some of the new variants strain, it may be that you can still get infected with the new strain, even if you've been vaccinated.
"It may well give you some protection about ending up in hospital but it may mean if you're infected, you may be able to still spread and transmit the virus."
Rotorua Area Primary Health Services was unable to comment.