Experts are warning some current vaccination policies are not enough to prevent the resurgence of measles that many countries are experiencing, "including New Zealand".
A new study published in the journal BMC Medicine, found current vaccination policies may be insufficient in preventing the disease breaking out in some countries and recommends compulsory vaccinations for first year students.
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The study was completed by a team of researchers at the Bruno Kessler Foundation and Italy's Bocconi University and modelled how current policies would affect the rates of measles between 2018 and 2050.
They also analysed the effect of adjustments to existing strategies.
The goal is to maintain the elimination of measles, which can cause a body rash and flu-like symptoms that can be life-threatening.
For measles to be eliminated, endemic transmission within a defined geographic area would need to be absent for more than 12 months or for the proportion of the population without immunity to be less than 7.5 percent.
The researchers focussed on seven countries with a two-dose measles vaccination programme and a high primary school involvement rate, but with different demographics and vaccination histories.
The countries were Australia, Ireland, Italy, Singapore, South Korea, the United Kingdom and the United States.
The study found that if policies were not changed, by 2050, the proportion of the population susceptible to measles would only remain below 7.5 percent in Singapore and South Korea - two countries with high vaccination coverage.
The other countries would hit more than 7.5 percent by 2050 if vaccination programmes were not extended. Italy was already at 9.3 percent in 2018 and would hit 10 percent by 2050 even if coverage reaches 100 percent.
It comes as countries, like New Zealand, see a "resurgence of the disease" and researchers warn the countries analysed need to do more to strengthen immunisation efforts.
"This resurgence is due to suboptimal vaccination coverage levels," said author Dr Filippo Trentini.
One author said the countries may want to look at compulsory vaccinations for first year students.
"Our results suggest that most of the countries we have studied would strongly benefit from the introduction of compulsory vaccination at school entry in addition to current immunisation programmes," said Dr Stefano Merler.
"We found that this strategy would allow the UK, Ireland and the US to reach stable herd immunity levels in the next decades, which means that a sufficiently high proportion of individuals are immune to the disease to avoid future outbreaks.
"To be effective, mandatory vaccination at school entry would need to cover more than 40 percent of the population."
There have been 111 confirmed measles cases in New Zealand this year, 95 of which were people who were not fully vaccinated.
Only eight occurred in people who were fully vaccinated against the disease and the remainder were partially vaccinated.
Ministry of Health director of public health Dr Caroline McElnay told Newshub it's a priority to have all children vaccinated.
Figures how of the 111 confirmed cases to May 3, 56 were in those aged 19 and below.
The MMR vaccine is free for those aged under 50 who have not had two documented doses.