The World Health Organization (WHO) has listed their top ten threats to world health in 2019. They include public health issues, environmental issues, problems with health delivery, and specific diseases that are of particular threat. One item on the list caught our eye because it is a frequent target of discussion on SBM, and is unique on the list in that the entire problem is essentially misinformation – vaccine hesitancy. They write:

Vaccine hesitancy – the reluctance or refusal to vaccinate despite the availability of vaccines – threatens to reverse progress made in tackling vaccine-preventable diseases. Vaccination is one of the most cost-effective ways of avoiding disease – it currently prevents 2-3 million deaths a year, and a further 1.5 million could be avoided if global coverage of vaccinations improved.

The antivaccine movement contributes significantly to 1.5 million deaths a year, has caused the resurgence of previously eliminated diseases, and has frustrated our ability to eradicate diseases like polio. We can’t entirely blame antivaccine pseudoscience for this, as there are other factors, such as availability of vaccines, and things like complacency and perceived inconvenience. But the impact of antivaccine propaganda is significant.

Let’s take a look at measles. In 2000 measles was eliminated from the US. Elimination means that there is no native reservoir of the disease, all cases are therefore imported from the outside (“eradication” refers to world-wide elimination). Since 2000, however, the number of cases of measles has been rebounding. It peaked in 2014 at 667 (remember the Disneyland outbreak?). In 2018 there were 349 cases, the second highest since 2000.

There are two main reasons for this increase. One is an increase in imported measles from overseas. This, in turn, is caused by an increase in worldwide measles cases. The imported cases, however, spread mainly through pockets of unvaccinated individuals – so the combination is particularly potent.

The WHO has not compiled their data for 2018 yet, but for 2017 they report:

Because of gaps in vaccination coverage, measles outbreaks occurred in all regions, while there were an estimated 110 000 deaths related to the disease.

Using updated disease modelling data, the report provides the most comprehensive estimates of measles trends over the last 17 years. It shows that since 2000, over 21 million lives have been saved through measles immunizations. However, reported cases increased by more than 30 percent worldwide from 2016.

And we know that 2018 was even worse. Europe was especially hit hard:

On October 17, 2018, the World Health Organization (WHO) reported 52,958 measles cases in the European region during 2018.

In all of 2017 there were 23,757 measles cases in Europe.

While there are always many complex factors involved when dealing with world health, in this case there is one giant factor looming over all others – vaccine hesitancy. The WHO is correct to call this out as a major health risk. In the case of vaccines, we have the science, and we have the means. Vaccines are an extremely cost-effective, safe and medically effective public health intervention, arguably the best public health measure ever developed. We also have the resources. The Bill and Melinda Gates foundation has made it their goal to vaccinate the world, and have donated billions of dollars to the cause. Vaccines are also a priority for the WHO.

The only thing we are lacking is the will, and only in a small minority of people. Unfortunately, because of the way community immunity works, pockets of vaccine hesitancy are enough to allow communicable diseases to spread. Eliminating and eradicating diseases like measles and polio takes a concerted worldwide effort over decades. Once an effective vaccine is introduced, there is a precipitous drop in the cases of the target disease. However, pushing those cases lower and lower requires more and more effort. Finally, eliminating or even eradicating a disease can take decades of consistent and thorough effort.

All of this time, resources, and determination can be wiped away relatively quickly, however. Decades of hard work can be undone when disease outbreaks are allowed to occur, when previously eliminated diseases become endemic again.

What is the solution? In their announcement the WHO outlined the problems, but did not propose a solution. Clearly, public education is important. Vaccine laws also have to be carefully crafted to make it as difficult as possible for parents to refuse to vaccinate their children, and measures need to be considered to protect vulnerable populations from the unvaccinated.

But there are deeper issues that will be extremely difficult to fix. One is the impact of social media. Social media platforms make it easy, in fact almost the default, to surround yourself in an echo chamber of your own views. In fact, algorithms may serve to radicalize views, so someone who simply has questions about vaccines may go down a social media rabbit hole of radical anti-vaccine propaganda. Major social media platforms need to reconsider how their algorithms work, which is happening, but it certainly hasn’t fixed the problem.

Social media, however, is partly just a reflection of human psychology. It may cater to the lowest common denominator, but mainly it has simply lifted the editorial cap that was previously limiting (but not preventing, to be sure) misinformation and exploitation. We are all content creators, content promoters, and content consumers. In a way, we get the social media we deserve. That doesn’t mean we shouldn’t explore ways to mitigate negative unintended consequences of this technology. I am not going to solve the social media problem here, but it does need to remain part of the conversation.

On the psychology end, again, we are not going to change basic human nature. But understanding that nature potentially gives us the ability to transcend it in a way that gives us more control over our lives. For example, recent studies have shown that those with anti-vaccine views are particularly susceptible to the Dunning-Kruger effect:

More than a third of respondents in our sample thought that they knew as much or more than doctors (36%) and scientists (34%) about the causes of autism. Our analysis indicates that this overconfidence is highest among those with low levels of knowledge about the causes of autism and those with high levels of misinformation endorsement. Further, our results suggest that this overconfidence is associated with opposition to mandatory vaccination policy.

People who hold anti-vaccine views think they know the most, even more than scientists, when in fact they know the least. What they have is an illusion of knowledge, created largely by the anti-vaccine social media echo chamber, but made possible by human psychology. Again, I don’t think there is a silver bullet for such a deep-seated problem, but there are factors that can improve the situation. Campaigns targeted at specific misinformation are important, and perhaps can help prevent those just starting to explore the issue from falling for a well-crafted conspiracy theory.

But targeted campaigns will not be enough. I think nothing less than a thorough revamp of science education is needed. We can do much better in crafting a scientifically literate population. But further, this is not just about a knowledge deficit, we can’t solve this problem by teaching facts. Science education needs to include the skills necessary to evaluate claims and sources, and to think critically. It should be the goal of public education for students to emerge from high school with the skills to survive in a world of massive misinformation.

And this education should not stop there, but needs to be lifelong. This further means that that standard for science journalism needs to be increased significantly. This is clearly not going to happen on its own, and if anything has been getting worse. I am not sure of the answer here either, but I do think that a solution will require a massive change in the scientific, academic, and professional communities. Specifically, they need to recognize quality science communication as a high priority. They can no longer be passive regarding the public understanding of science.

The WHO recognizes that vaccine hesitancy is a major worldwide health risk. If it’s a health risk, then it is worth addressing. That means it needs to be a real priority, which in turn means resources, not just platitudes. The medical profession in particular is flat-out losing the war of public opinion regarding science and medicine, largely because they have not realized that the war even exists.


Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also has produced two courses with The Great Courses, and published a book on critical thinking - also called The Skeptics Guide to the Universe.