Ministry of Health figures showed 59.7 per cent of children in the Western Bay of Plenty at the age of 18 months were fully immunised in the most deprived areas - compared to 78.5 per cent of children in the least deprived areas.
Figures are slightly higher in the Lakes District with 70.8 per cent of children aged 18 months fully immunised in the most deprived areas compared to 84.5 per cent of children in the least deprived areas.
The figures were calculated using the New Zealand Index of Deprivation, an area-based measure of socioeconomic deprivation that uses Census data.
Eighteen per cent of the Western Bay of Plenty's total population and 38 per cent of Rotorua's total population live in the most deprived areas, according to this data.
Te Uarangi Teepa's experience of being immunised as a child and a resonating conversation with her kuia meant immunising her babies was a natural progression.
"One of my kuia told us how she gave birth to 15 children but only seven survived because eight of them died of influenza as babies, although this was generations ago.
"But Pākehā diseases need Pākehā medicine. These diseases are introduced so we need the proper protection we don't naturally have."
Toi Te Ora medical officer of health Dr Jim Miller said inequities in the uptake of immunisations were unacceptable and were visible across the country.
"There are gaps in the uptake of immunisation at each of the milestone ages. These gaps need to close along with an overall increase in immunisation uptake.
"We need an equitable and much better overall uptake of 95 per cent to ensure there are no outbreaks of diseases like measles, and to help protect vulnerable babies from whooping cough."
The recent measles outbreak was a reminder of how important vaccination is in protecting people from illnesses, Ministry of Health spokeswoman Vicki Carter said.
Since January 1, the Bay of Plenty has had 63 confirmed cases of measles, of which 23 have been admitted to hospital. Miller said all immunisations were important.
Lakes DHB portfolio manager Pip King said she was aware immunisation rates had been dropping in Rotorua.
"Rates for babies in the most deprived neighbourhoods and Māori children are particularly low.
"This is not acceptable as a 95 per cent immunisation rate is necessary to protect the whole population."
Pinnacle Midlands PHO medical director and Bay of Plenty general practitioner Dr Jo Scott- Jones said it was a common feature for lower socio-economic groups to have worse health outcomes but often lack of accessibility made it hard for those communities to get the best medical care.
"I don't come across people that don't want vaccinations through cultural beliefs but we are seeing more people declining due to their particular health beliefs.
"What is also concerning is we are seeing a higher number of people in the least deprived areas aren't getting vaccinations due to their health beliefs and that is something the public health system needs to grapple."
Western Bay Primary Health Organisation co-chairman Paora Stanley said the low statistics for deprived areas was due to one big reason - accessibility.
However, it was the idea of being on a register and being forced to move around that created accessibility problems for "vulnerable communities" Stanely said.
In that case, outreach nurses were tasked with finding those people, but he believed they did not have the connections to be successful.
"We have got to stop disconnected health professionals trying to talk to disconnected people.
"To help them, we need the right people knowing where to go."
Like the Lakes DHB, the Bay of Plenty DHB's child, youth and oral health portfolio manager Tim Slow said the health service was trying to improve access and engagement for people who have greater access issues due to poverty, rural isolation and complexity.
"This includes outreach nurse visits to the home and opportunistic visits to venues where parents and children are present."
Slow said many factors impacted on low immunisation rates, including "high levels" of declines, finding or contacting parents, and maintaining training with staff who manage the immunisation conversation with parents.
The most deprived areas throughout the Bay of Plenty:
Western Bay of PlentyMatapihi Kairua Yatton Park Tauranga Hospital Greerton Gate Pa Te Puke West Te Puke East Maketu Paengaroa