The Bay of Plenty is at the start of a whooping cough outbreak and the region's health board is calling on parents to immunise children.
Medical officer of health for the Bay of Plenty and Lakes Dr Neil de Wet said the Bay was at "the beginning" of an outbreak following a South Island trend of a large increase in whooping cough cases.
Thirty-two cases of whooping cough had been diagnosed in the Bay since January, and 1322 nationally.
This week is World Immunisation Week and prevention via vaccination is of primary importance, said Dr de Wet.
He said whopping cough, or Pertussis as it was known by medical experts, could be "serious" in children aged under one. A large number of diagnosed babies required hospitalisation.
Symptoms were initially mild, then developed into severe coughing fits which produced the namesake high-pitched "whoop" sound in infected babies and children when they inhaled air after coughing.
Dr de Wet said Tauranga recorded a 91 per cent success rate in the number of 2-year-olds who had been fully immunised, compared to a national target of 95 per cent in the latest round of health targets.
The national average of 2-year-olds being fully vaccinated was 92 per cent. Only 495 extra children who are about to turn 2, needed to be immunised before June 30, for New Zealand to achieve the 95 per cent immunisation coverage recommended by the World Health Organisation this quarter.
The Bay's immunisation figures had risen steadily in recent years due to a concerted effort by the local health sector, particularly GPs and nurses, Dr de Wet said.
"Our own surveys and our experience is the overwhelming majority are very supportive of immunisation. GPs and the Primary Health Organisation have worked hard to promote immunisation."
However, full immunisation coverage of babies at the six-month mark was not as good.
"It signals that for some, there's a delay in getting immunised."
All standard childhood immunisation shots were free and parents should not be complacent, he said. In October and November last year, there was a measles outbreak and while numbers had since fallen, it was still important to be immunised. The same went for meningitis.
There were currently two available vaccines in the schedule that protected against two types of meningitis - they were pneumococcal and haemophilus.
There were other types of bacteria that could cause meningitis however, including meningococcal.
World Immunisation Week runs until April 29.
Experts said children should be vaccinated at 6 weeks, 3 months, 5 months, 15 months, 4 years and 11 years.
Dr de Wet said immunising children on time, ensured they had the best protection against a range of serious diseases.
Health Minister Tony Ryall said about 90 per cent of New Zealanders support immunisation.
About 5 per cent chose not to immunise, which leaves a group who haven't made a decision or have not got around to it.
"These are the parents we are working hard to reach to achieve our target of 95 per cent coverage of 2-year-olds by July this year."
A free drop-in clinic was running throughout immunisation week at The Tauranga Early Years Service Hub in Garden Place.
The Hub would give children up to 6-years-old an chance to get up to date with their immunisations, and no appointment was necessary.