Infectious disease experts have warned that a generation of New Zealanders are still vulnerable to contracting measles due to a lack of national approach.
Health Ministry documents revealed the Ministry received expert advice in 2017 on the urgent need to get more young people immunised.
The rise in measles cases comes amid increasing concern around the so-called "immunity gap": the generation of New Zealanders in their teens to mid-30s who are more likely than any other age group to not have received a vaccine.
The National Measles Elimination Verification Committee (NVC) met in May 2018, and recommended that "a systematic, programmatic approach" was needed.
But in a statement to RNZ, Doctor Nikki Turner, who chaired the meeting, says the immunity gap "still needs to be addressed".
Latest figures show that there have been 311 confirmed cases of measles in New Zealand this year, taking it higher than the outbreak in 2014, when 280 cases were confirmed.
Institute for Environmental and Scientific Research public health physician Sarah Jeffries said there were four main areas where the outbreaks were focused, but most cases were coming from the Auckland region.
Some 206 confirmed measles cases were in individuals who had not been immunised.
Measles just a plane ride away
Public health clinicians today warned passengers from two domestic flights in the first weekend of July - flight NZ5119 between Auckland and Palmerston North and flight NZ5114 between Auckland and New Plymouth that they had been exposed to the virus.
Auckland Regional Public Health Service said in the Palmerston North case, a passenger flew while infectious before knowing they had the preventable disease.
"This particular case demonstrates how infectious diseases can spread so easily through the community," Health Service clinical director Julia Peters said.
"I think the general message to everybody in Auckland is that we need infants who are twelve months of age to be getting their first MMR vaccine at twelve months. So we've brought that forwards from 15 months," Dr Peters said.
"We need anyone who is under 50 years old who is unsure whether they've had a MMR vaccine, or unsure about their immune status, to see their doctors and have a vaccination.
"It's much better to get a vaccine. There's no harm in having an extra one, [better] than to wait around for blood tests to demonstrate whether you're immune or not. So my message to people is that the only way we are going to bring the outbreak under control is for people to get vaccinated."
It brings the total number of measles warnings on domestic flights up to four this month.
Mind the 'immunity gap'
Recently-revealed documents show the Ministry of Health has been sitting on advice from a group of experts as to how to reduce the immunity gap.
A 2018 meeting of the NVC outlined several measures that could be put in place to help. Amongst various options, they discussed possible options such as:
• Starting an adult vaccination programme, as was practiced in the US • Designing an entirely new IT system • Need for additional funding to support vaccination strategies • Implementation of border control measures • Use of travel doctors
An earlier meeting in 2017 further laid out a twelve-point plan including options to introduce immunisation registers in secondary schools and universities, as well as offering universal funded MMR for people aged 12 to 32.
So far this year, babies under 15 months old had the highest number of unvaccinated cases. Such young babies do not typically receive vaccinations, although the age has recently been lowered to 12 months.
They were followed by the 10-19 age group, with 64 confirmed cases. Of those, 42 were confirmed as unvaccinated, another 16 were 'unknown' and two more had only had one dose.
Third was 20-29 year-olds with 76 confirmed cases, 37 of whom were confirmed not vaccinated (plus 25 unknown and five with only one dose).
In a statement to RNZ, Director of Public Health Caroline McElnay said the Ministry of Health was reviewing the best approach to ensure the "immunity gap" age group took up the free vaccines.
Dr McElnay said the ministry was working with district health boards and public health units, and had funded a public information campaign including a radio campaign costing $35,659 that specifically promoted immunisation for young adults.
University of Auckland senior lecturer Helen Petousis-Harris, who is director of the Vaccine Datalink and Research Group, said the Ministry of Health needed to act now.
"I think they've had all the expert advice that they need," she said. "The ball is in their court.
"We just have to continue to hope that we will be able to plug these gaps but I think that we're all sounding like a bit of a stuck record.
"We've had these ongoing outbreaks for years now, and every time we say the same thing: that we've really got to get these people in these age groups vaccinated because we have relatively low coverage among our 10-29 year-olds."
Dr Petousis-Harris said there also needed to be more of a concerted effort to ensure future outbreaks did not occur.
"If we go by history ... this is a cycle that continues, although I think there's been a bigger move this time for people to go and seek vaccination.
"We're still having the outbreak, we haven't got there yet.
"But yes, history will dictate that we will quickly forget about it until the next time.
"I think we're going to see a lot more of these outbreaks, given the global situation with measles, given there's a resurgence in many countries. It's going to keep walking off the plane into these communities. So until we deal with it, it's going to continue to happen."