Most parents who opt-out of vaccinations are being guided by "irrational fears" that are a luxury of living in the developed world, a leading world health expert says.
In this week's Scrubbing Up, Dr Seth Berkley, CEO of the GAVI Alliance - which provides children in developing countries with access to vaccines - says there is a real danger such fears will trickle down into the developing world where lives are even more vulnerable.
With the measles outbreak in Swansea possibly having claimed its first life and as the number of cases continues to rise, it's easy to stand back and put it all down to the legacy of Dr Andrew Wakefield.
But while the discredited paediatrician should certainly take some of the blame - for undermining public trust in the safety of the MMR vaccine 15 years ago - the truth is that the problem goes much deeper and is more dangerous.
Anti-vaccine sentiment has been around almost as long as vaccines themselves.
Opponents of vaccines often claim a range of different reasons or justifications for their opposition, but for the majority of people who are swayed by these minority voices - enough to choose not to vaccinate their children - it usually comes down to nothing more than fear.
Ironically when vaccination rates fall, they end up facing a real but very different kind of fear.
Indeed as parents in Wales take their place in line at catch-up clinics to have their children and teenagers vaccinated - the so-called "missing generation" - they are in the unenviable position of seeing first-hand what it is like for parents in developing countries.
The difference is, those in Wales had a choice.
In many parts of the world measles is still a killer, claiming the lives of 164,000 under-fives every year, or around 450 children every day.
No parent would willingly choose to endanger their child, and nor would they have taken the decision not to vaccinate lightly.
Wakefield's scaremongering tapped into an inherent and pre-existing fear or mistrust of vaccines that has long existed among some parents.
The question is, where does this mistrust come from?
As a medical doctor and scientist I personally find it very difficult to understand.
To me, vaccines are quite simply amazing; the way in which one little injection can prevent so much suffering and death makes them in my mind the closest thing to a scientific miracle.
In wealthy countries most of us have either forgotten or never knew the horror of these diseases.
Jail term threat
As an American and as CEO of the GAVI Alliance, a non-profit organisation that has purchased vaccines for more than a third of a billion of the world's poorest children over the past decade, preventing more than 5.5 million deaths, I find myself straddling two very different worlds.
On the one hand I see the devastation that vaccine-preventable diseases cause, and I see parents in developing countries who have witnessed this and are prepared to walk great distances and wait in line for the chance to vaccinate their children.
Yet at the same time I meet parents back home and in Europe who have genuine concerns about the safety of vaccinating their children.
Some people argue that such anxiety comes from a visceral fear of having someone who is not ill deliberately injected with or ingesting a pathogen, live or otherwise.
But I don't buy into this, people are smarter than that.
If we could take headache pills before the pain set in we would do so, and usually without reading the small-print to see what remote risks this might entail.
Others suggest that vaccines are merely a proxy for the nanny state.
Yet unlike France, where parents are not allowed to enrol their children in state primary school without proof of immunisations, or Uganda, where legislation is currently being considered that would see parents jailed for six months for failing to have their children vaccinated, the people of Swansea were in no way compelled to vaccinate their children.
In fact if it were not for the safety nets of mass vaccination and good health services provided by their governments, parents in wealthy countries wouldn't be in a position to make a choice about vaccination, or at least risk choosing not to vaccinate.
Indeed, this issue of mistrust is not about whether vaccines work.
On the contrary, parents who opt out are very much counting on it, relying on everyone else to provide the herd immunity they have so willingly rejected.
The beauty of a free society is that people are entitled to think and act like this.
The trouble is, what happens when everyone does so?
It is only then that the fear of a remote possibility of your child having an adverse reaction to the vaccine is replaced by the far more immediate risk that they could become seriously ill.
That is when we start to see the lines forming.
There will always be some people who make the conscious and somewhat cynical decision to play the numbers game, relying on others to protect their child.
But for most people the decision comes down to a "feeling" that has little to do with rationality.
Like a fear of spiders or other forms of irrational fear, often all it takes is a trigger - in this case in the form of an outspoken anti-vaccine zealot, who may even wear a white coat, to bring those fears to the surface.
The people in Swansea are now paying the price for this irrational fear, but hopefully no more will pay with their lives.
Even more worrying is when such fears begin to trickle into countries like India, where lives are more vulnerable and the stakes are far higher, then the situation can become even more dangerous.
And indeed, thanks to a small yet vocal anti-vaccine minority, this is precisely what is now happening in India.
The lesson to be learned is that it is not the Wakefields in the world that we need to worry about, there will always be opponents to vaccines.
Rather it is our own fears and doubts that these people are so adept at manipulating and leveraging that we need to fear the most.