Coming up against people who choose not to vaccinate can be frustrating. It's even worse when you realise that those who question the safety of vaccines are often logical and well-educated in all other aspects of their life... but when it comes to vaccines? No amount of peer-reviewed evidence will change their mind.
But research has shown that there is a way to get anti-vaxxers to realise the importance and safety of immunisations. And it doesn't involve arguing with them.
In fact, research has shown that beating people across the head with facts they don't agree with only makes them more convinced of their existing beliefs.
In other words, it doesn't matter how many times you tell an anti-vaxxer that, no, there haven't been any mercury products in vaccines since 2000.
But a 2015 study on 315 people showed there is a tactic that works - show them the alternatives to vaccines.
The study took three groups containing anti-vaxxers and tried three approaches to change their minds:
- giving facts on the safety of vaccines from the Centers for Disease Control and Prevention (CDC);
- getting them to read an unrelated statement about bird feeding;
- or showing them photos of vaccine preventable diseases, and the personal account of a woman whose 10-month-old son almost died from measles.
That second group served as a control, but, surprisingly, the bird feeding statement had the same impact on the anti-vaxxers as the facts from the CDC - which is, no impact at all.
The third group, however - the one given graphic images and stories of diseases such as measles and smallpox - showed a significant positive shift in their thoughts on vaccines.
Focussing on why vaccines are so crucial, rather than arguing about how safe they are, was the most powerful weapon to change people's minds.
It was a small study, but it echoes a larger body of research on how to change people's minds.
"It's more effective to accentuate the positive reasons to vaccinate and take a non-confrontational approach - 'Here are reasons to get vaccinated' - than directly trying to counter the negative arguments against vaccines," said lead researcher Keith Holyoak from the University of California, Los Angeles, back in 2015.
"There was a reason we all got vaccinated: Measles makes you very sick. That gets forgotten in the polarising debate on whether the vaccine has side effects."
This makes sense when you look at what motivates anti-vaxxers - despite what some might think, those who choose not to vaccinate their children care deeply for their kids' safety and are driven by morals, just like those who vaccinate their offspring.
But a recent study showed that the morals that drive the two groups are very different.
Importantly, anti-vaxxers place great importance on two morals in particular: individual liberty and purity.
Liberty in this context meant that they believed in personal responsibility, freedom, property rights, and resistance to state involvement in people's lives.
Purity referred to the importance they placed on boundaries from protection and contamination.
When you think about those core values, it makes sense that trying to debunk their concerns about vaccines could have the opposite effect - having other people share opinions on what they should and shouldn't do with their family goes against their sense of personal liberty.
With almost 9 million children in the US alone at risk of contracting measles as a result of under-vaccination, and research showing that just a few anti-vaxxers can triple disease rates, it's more important than ever that people know what's really at stake when they choose not to immunise.
And the best way to do that, according to the science, is to forget about correcting false beliefs, and focus instead on the positives of vaccines, and the diseases they prevent. After all, we all want what's best for our families.
"Try not to be directly confrontational," advises Holyoak. "Try to find common ground, where possible, and build on that."