During 2000 the US declared that the measles virus had been eliminated. Despite a few outbreaks, most people had been vaccinated against measles. However, during 2019 the US saw 1282 confirmed cases in 31 states; most were amongst those who had not been vaccinated. Questions then arose about why people were not getting vaccinated.
Vaccine scepticism is the term given to people who are hesitant or unwilling to be vaccinated, a phenomenon that has become increasingly widespread. Attempting to explain this, researchers from the Texas Tech University Department of Psychological Sciences believe that some people find vaccines risky because they ‘overestimate the likelihood of negative events, particularly those that are rare.’
Publishing their work in the journal Vaccine, the researchers reported that the overestimations can carry over into many different negative events, not just those that related to vaccination. This, the researchers propose, suggests that people higher in vaccine scepticism may process information differently than people lower in vaccine scepticism.
In one experiment the researchers surveyed 158 people to determine the level of vaccine scepticism underlying their perceived dangers, feelings of powerlessness, disillusionment and trust in authorities regarding vaccines. Participants then estimated the frequency of death associated with 40 different causes, ranging from cancers, animal bites, childbirth and fireworks to flooding and car accidents. The researchers found that people with higher levels of vaccine scepticism overestimated the frequency of these events.
‘My understanding is that vaccine sceptics probably don’t have the best understanding of how likely or probable different events are,’ said Mark LaCour a doctoral student in psychology sciences. ‘They might be more easily swayed by anecdotal horror stories. For example your child could get a seizure from getting vaccinated. It’s extremely rare, but within the realm of possibility. If you are so inclined, you could follow Facebook groups that publicise extremely rare events. These cognitive distortions of anecdotes into trends are probably exacerbated by decisions to subscribe to statistically non-representative information sources.’
The researchers propose that there is a difference in the information being consumed and used by people with higher vaccine scepticism.
‘It may be the case that they are specifically seeking out biased information, for example, to confirm their sceptical beliefs. It could be that they [give more attention] to negative, mortality-related events, which makes them remember this information,’ said Tyler Davis PhD Assistant Professor Psychological Sciences Texas Tech University.
Strategies to get the right information to people through public service announcements or formal education may work, but it doesn’t seem to be an issue that people with higher vaccine scepticism are less educated in any fundamental way in terms of basic science or math education. Thus, simple increases in these alone – without targeted informational interventions – would seem unlikely to help, the researchers added.
Vaccine DOI: 10.1016/j.vaccine.2020.02.052