To Vax or Not to Vax: The Psychology of Anti-Vax Bias

“I didn’t vaccinate my baby because vaccines cause autism.”

“The side effects of vaccines are worse than the risk of the disease.”

“I know a person who got a vaccination and died.”

“Read this on the internet about the dangers of vaccinations.”

Since the COVID-19 pandemic, but even before that, I have encountered friends, relatives, and acquaintances who have tried to make decisions about whether they should vaccinate themselves or their kids. I’m sure many of you have heard these sorts of statements, too.

Often, when people try to make these health-related decisions, they fall victim to common psychological biases in their decision-making processes. My intent here is to provide information to help cut through flawed decision-making and help people make sound, informed decisions about vaccinations (and other decisions regarding medical procedures) that are free from bias.

First, let me be upfront about my own bias. I am a social scientist and grew up in a medical family. For the most part, I trust science and medical research and believe that government agencies, like the Centers for Disease Control and Prevention (CDC), rely on scientific evidence when they approve vaccines and medical interventions. Their goal is to protect people, and they try their best to do that. (Yes, drug companies are profit-driven entities that may have other motives, but that’s why the government has oversight on approving vaccines.)

Here are factors that need to be considered when deciding about vaccinations and other medical procedures.

Trust the Experts

It is important to seek out trusted, expert sources when seeking information about health issues. The National Institutes of Health, the CDC, and other reputable websites will try to provide the most sound, objective information to guide your decision-making. Relying on the X app or other platforms that are full of disinformation to make health-related decisions is not a good idea. Here is a resource to trusted sites about your health.

Dangers Relying on Personal Experiences Over Science

Instead of seeking expert information, many people rely on their own experiences or the experiences of others to make decisions. There is a serious problem with this, as fundamental human biases come into play to disrupt sound decision-making. What are these psychological biases that can lead us down the wrong path? Here they are (and here is your psychology lesson for today.):

Correlation and Causality. “I got vaccinated, and a week later, I got sick, and the same thing happened to my friend.” Just because two things occur together in time—are correlated—does not mean that one thing caused another. A common bias we are all prone to is assuming that correlated events determine causation, which is not the case.

Small Sample Size. “I’ve spoken to several people who have all had bad reactions to their vaccination, and one person was hospitalized.” Again, relying on our personal experiences or the experiences of others is no way to make a decision about one’s health. Of course, there are side effects of vaccinations, drugs, and medical procedures. Still, the scientific results that led to the approval of medical interventions are based on thousands of cases, not just a handful.

Confirmation Bias. “It’s not just one person who had a bad reaction to the vaccine, but I’m hearing about others having the same outcome, over and over again.” It is a common bias to search for information that confirms our beliefs or hypotheses and ignore disconfirming information. This tends to “cement” the decision: “I was right all along.”

Vividness Heuristic. “But someone died after getting a vaccination.” We tend to pay greater attention to vivid, extreme incidents and outcomes and ignore that there are no dramatic, negative outcomes most of the time. This is the same reason why people’s fear of flying (and decisions not to travel) increases after a well-publicized plane crash.

Hindsight Bias. “I got vaccinated and got sick. I’ll never get vaccinated again.” This is the I-told-you-so-effect. After the fact, we tend to look back, and coupled with some of the other biases above, we mentally reconstruct and use this biased information to guide our future actions.

What To Do

First, seek reliable and objective scientific information from trusted sources in making any decisions about your health.

Second, be aware of biases that occur naturally in our decision-making. Don’t rely on what you’ve heard from others or your observations without considering the bigger picture.