It’s tempting to lump non-vaccinators into a single category, a politically charged cohort of angry commenters and conspiracy theorists who believe that vaccines cause autism despite all scientific evidence to the contrary. In reality, though, it’s more complicated.
In fact, that description represents just one of four different behavioral patterns that lead to vaccine refusal, according to a study published this month in the journal Policy Insights from the Behavioral and Brain Sciences. The study broke vaccine refusal into four broad categories: complacency, inconvenience, a lack of confidence, and a rational calculation of pros and cons.
“Vaccination is one of the most effective public health interventions,” said Cornelia Betsch, a study author and scientific manager of the Center of Empirical Research in Economics and Behavioral Sciences at the Universität Erfurt in Germany. In addition to reducing societal inequities and poverty, vaccines have been proven safe and effective many times over, with some public health experts going so far as to argue that vaccination should be as non-negotiable as wearing a seat belt.
But in order for a population to be protected from an infectious disease, such as polio or measles, a critical number of people in the community must be immunized. This concept is known as herd immunity. Once the immunization rate falls below 95 percent of the population for measles, or 85 percent of the population for polio, those who are too young or too sick to receive vaccines are left vulnerable to disease.
“From a public health point of view, it is important to understand what the barriers and enablers of vaccination are,” said Betsch, who spoke on behalf of the research team.
Distinction is key. If we better understand the nuances in non-vaccinators’ psychological processes, we can be more effective in establishing targeted public health campaigns and interventions that bolster vaccination rates.
Here are the four types of people who don’t get vaccinated:
1. The Passive Shot Skipper
Motivating factor: Complacence
What this means: Complacent individuals think that the risk of vaccine-preventable diseases is relatively low, and don't feel threatened by the risk of being infected. If people don't feel threatened, they're unlikely to take measures to protect themselves.
A complacent person probably hasn't gotten vaccinated in the past, continuing to avoid vaccines is a habit rather than a conscious decision. "Complacent people passively omit vaccination rather than actively decide against it," the researchers wrote in the study.
Targeted intervention: This group needs more information to understand the risk of disease and the social benefit of vaccination. A strong recommendation to vaccinate from the patient's doctor, as well social campaigns that highlight vaccination as a societal norm, could also go a long way toward motivating complacent individuals to make immunization a habit.
2. The I'll Do It Tomorrow-er
Motivating factor: Convenience
What that means: People who don't vaccinate because of convenience may face physical obstacles to immunization, such as cost, availability, travel time and education barriers, like language and health literacy. Personal barriers can also get in the way of people in this group, who may want to vaccinate, but keep pushing off their appointment in favor of other commitments or priorities. Psychologists refer to this as the intention-behavior gap, indicating it's a case of when good intentions aren't enough to facilitate follow-through action.
Targeted intervention: It's all about eliminating structural barriers for convenience-challenged people. In addition to making vaccines affordable and widely availably, making immunization the default option -- enacting an opt-out rather than an opt-in policy -- is one effective intervention.
For example, in a study published in the Journal of the American Medical Association in 2010, people who were prescheduled for a flu shot appointment they could opt to cancel were more likely to vaccinate than those who weren't prescheduled.
According to the study authors, "This intervention capitalizes on the default effect or the tendency for people to stick with the option they will get automatically if they do not take explicit action."
3. The Political Anti-Vaxxer
Motivating factor: Lack of confidence
What that means: This is the group you read about in the news. People in this group don't trust the safety and efficacy of vaccines, and moreover, don't trust the health professionals and government officials who recommend them. In contrast to the two groups above, lack-of-confidence people have negative opinions of vaccines, and may traffic in misinformation about the risks of vaccination.
Targeted response: Because this group feels so strongly about vaccines, their opinion is notoriously difficult to change. Indeed, a 2014 study published in the journal Pediatrics showed that trying to talk sense into staunch anti-vaxxers was not only ineffective, but in some cases actually increased misperceptions and decreased vaccination rates. "Paradoxically, if you put too much effort in persuading them, they may be reactant, which may lead to an even stronger wish to hold on to their own points of view," the study authors explained.
So are avowed anti-vaxxers a lost cause? Not necessarily. "This group needs very special care," the study authors wrote. "If people have questions, they should be taken seriously and receive answers in a way they can digest. Anything that rebuilds trust in both the system and in vaccination as a public health measure should also be worth a try."
4. The Researcher
Motivating factor: Utility calculation
What that means: This group extensively researches the pros and cons of vaccination before making a decision. If a utility calculator decides that her chance of having an adverse reaction to a vaccine is higher than her chance of contracting measles or getting the flu, for example, she might choose not to vaccinate. The problem with this line of thinking is that it disrupts herd immunity. (Others take a more self-serving approach, and conclude that if other people vaccinate, they'll be safe, too.) If enough healthy people weigh the pros and cons of vaccination and decide not to vaccinate, herd immunity disintegrates and everyone's risk of infection goes up.
Targeted response: Internet research is great, but there's a lot of misinformation out there. In the case of rational decision-makers who weigh the pros and cons before immunizing, it's extremely important to provide accurate information and to correct any misinformation they may encounter in their research process. Any information that stresses the utility of vaccination is likely to appeal to these pragmatic individuals.
Clarification: Language has been added to reflect that herd immunity varies by disease, and that the previously stated vaccination rate of 95 percent applies to measles, but not to other diseases.
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