Dr Richard Medlicott has been seeing patients for two decades and hasn't once encountered a case of mumps, measles, diphtheria or tetanus.

"That's not to say we don't get outbreaks occasionally - but you just don't see it, because there's much less of it around."

That wouldn't have been the case for the Wellington GP's father, who was also a doctor.

He put the difference down to one factor: childhood immunisation.

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"We follow the evidence, and there is overwhelming evidence that immunisation is safe, effective and one of the best public health interventions we've got - most GPs know that."

A new study published today in the New Zealand Medical Journal found nearly 98 per cent of GPs and doctors surveyed, and 90 per cent of pharmacists, had a level of confidence in standard childhood immunisations.

The data came from the New Zealand Attitudes and Values Study (NZAVS), a longitudinal effort run by the University of Auckland, and captured rates as at 2013-14.

"What we were looking to do was show that, among doctors, there was a very strong consensus that vaccinations are safe," the study's author and doctoral candidate Carol Lee said.

"We thought that might be useful for the public to be aware of, because those are the people that we should be listening to."

Lee likened the finding to research that showed the overwhelming majority of climate scientists agreed human-driven climate change was happening.

However, the study indicated confidence wasn't as high among midwives, at 65.1 per cent, and perhaps less surprisingly, practitioners of alternative medicine weren't very confident at all (13.6 per cent).

Study co-author Professor Chris Sibley said the lower rate among midwives warranted further investigation.

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"We didn't expect that finding, but we do think it highlights something that will be very useful and important for doing further research on."

Associate Professor Nikki Turner, a GP and director of the University of Auckland-based Immunisation Advisory Centre, saw one possible explanation.

"Traditionally, we didn't use to vaccinate in pregnancy, and over the last few years, what we know from really good evidence is pregnancy vaccinations for flu and whooping cough protects the newborn baby because the mum passes it through the placenta," Turner said.

"So this is relatively new. And antenatal providers, not just midwives, more and more are beginning to understand the evidence base behind pregnancy vaccinations."

Turner said it was no surprise the vast majority of doctors backed vaccination.

"They say that some of the greatest achievements in public health are sanitation, nutrition, hygiene and childhood vaccination programmes."

"We follow the evidence, and there is overwhelming evidence that immunisation is safe, effective and one of the best public health interventions we've got - most GPs know that," Dr Richard Medlicott says.

Despite the overwhelming scientific consensus, there have been concerns among some health professionals that anti-vaccination sentiment is on the rise in New Zealand.

While the Ministry of Health has goals to increase immunisation rates to 95 per cent for 8-month-olds, the latest coverage rate report found that, over the three months to December, the number fell short of that mark at 92 per cent.

It was also down on coverage rates at the same time in 2016 (93.3 per cent) and in 2015 (93.7 per cent).

New Zealand's Environmental Protection Authority recently listed anti-vaccination as among areas where misinformed views were being reinforced and nurtured in what it called the "unmoderated milieu" of the internet.

Last year, Kaitaia GP Dr Lance O'Sullivan felt compelled to storm the stage at a local screening of a controversial film incorrectly linking vaccines to autism."

I think there is a little bit of concern when you see misinformation being spread, and patients or their parents find it difficult to tell what is reputable and what isn't," Medlicott said.

"And children become at risk because of it. At the end of the day, these are individual choices, but we do get concerned when we see false information out there."

Study finds problem with drug prescribing

Meanwhile, another study featured in the New Zealand Medical Journal suggested prescribers did not always follow guidelines when prescribing other medicines to patients taking a cholesterol-lowering drug.

Simvastatin is a cholesterol-lowering drug widely used in New Zealand to prevent major cardiovascular events such as heart attacks and stroke.

However, some medicines can inhibit the activity of the enzyme, named CYP3A4, that metabolises simvastatin and this can lead to high levels of simvastatin in the blood, which in turn increases the risk of side effects.

Prescribing guidelines state that some medicines which inhibit CYP3A4 should not be prescribed to people taking simvastatin – these are "contraindicated medicines".

And, some medicines should only be used with caution and careful management of the simvastatin dose – these are known as "use-with-caution medicines".

In a nationwide study, University of Otago researchers from the Pharmacoepidemiology Research Network found that despite the existence of prescribing guidelines and patient management software – which alerts prescribers to potential drug interactions - 11 per cent of patients were dispensed a contraindicated medicine during the first two years of simvastatin use.

A further 16 per cent were dispensed a use-with-caution medicine.

These proportions increased over time. By seven years, 17 per cent of patients had been dispensed a contraindicated medicine and 26 per cent had been dispensed a use-with-caution medicine.

In the majority of cases, the prescriber of simvastatin and the contraindicated or use-with-caution medicine were the same.

One of the study's authors, Dr Lianne Parkin, said a large number of patients received a contraindicated or use-with-caution medicine on more than one occasion.

"These co-prescribing events were not always isolated incidents – for many patients they occurred more than once."

Further work was required to explore and address the reasons for such co-prescribing, the researchers said.