How does vaccination work?

Vaccination is important because it has two roles, said Sydney paediatrician Dr Scott Dunlop.

"At an individual level, it provides antibodies for individuals to protect them against infections they may come in contact with in the future and in doing so contributes to herd immunity," he said.

"Herd immunity says that if the majority of the population is protected from a certain infection [through vaccination], then the likelihood of that infection increasing in incidence is much lower.

"Legitimate reasons for not getting vaccinated include if someone has a rare immunodeficiency syndrome they can't be vaccinated with a live vaccine. The other reason is if you've had a severe reaction to a vaccine previously - that is very uncommon," he said.

The problem is that there's a trend towards not vaccinating, albeit at a small rate but if the trend continues it will see outbursts of infection otherwise not encountered.

"In my experience sometimes people [in Australia] choose to delay the hepatitis B vaccination which babies normally get at birth, instead getting it at 12 months. The other choice I see is, 'do I vaccinate or do I not vaccinate all together?'," said Dr Dunlop.

"Some people ask if they can split the vaccines up into individual shots but in Australia it's generally not possible because the vaccines are not available as individual shots - they are polyvalent vaccines.

"If I have a patient wants to have a discussion around immunisation I present them information and ultimately I think it's their decision on what they want to do. However my individual clinician view is that those who don't immunise their children are foolish, uneducated and arrogant.''

Miseducation and poor decisions

"There's a problem in how people access information and then interpret that information when they're not scientifically educated and that's no different than me telling my mechanic a better way to do his job just because I've read something online about it.

"The other issue is people actively seeking information that supports their decision not to vaccinate, because they've decided they want to go against the status quo or that they think the pharmaceutical industry has an agenda that comes down solely down to commercialisation," said Dr Dunlop.

The consequences of falling rates of vaccination includes a greater load on the health system and an increased risk to other children as once-rare diseases become more prevalent.

How to communicate with doubters

"I support measures that might discourage people from taking an anti-vaccination stance such as no jab no play and no jab no pay for their childcare benefit - and excluding kids from public spaces is very reasonable," said Dr Dunlop. "This is a serious population health issue and parents that decide they're going to be different and not vaccinate need to take on the consequences of that decision.

"When the evidence is overwhelming that vaccination is of benefit to the population, the majority should stand up and criticise that minority and exclude them as necessary.

"A vaccine hesitant person is someone who's still open minded and will hopefully make a correct decision once the evidence is presented to them in a logical and sensible way. They don't deserve aggression - they are uninformed but open to being informed.

"The growing popular anti-vax movement should be aggressively countered because it's an ideology, it's not based on evidence or common sense. It puts people at risk and it should be called out for that.

"People shouldn't be listening to people on social media for health advice; they should go and speak with their GP. My job is to advocate for evidence-based medicine, and that's all [promoting vaccination] is doing," he said.