Inoculating against misinformation

Ella Rhodes on 'vaccine hesitancy'.

Measles cases increased by 300 per cent globally in the first three months of this year compared with the same period last year, according to World Health Organization figures. A recent analysis by Unicef also found more than 500,000 children in the UK did not receive their first measles vaccination between 2010 and 2017; globally, this number was 169 million.

While the drivers of these trends are likely to be complex, particularly when considered on a global scale, one concern is the role of vaccination conspiracy theories in so-called ‘vaccine hesitancy’. I spoke to two psychologists who are looking into novel ways to tackle beliefs in misinformation.

While there are numerous reasons parents choose not to vaccinate their children, some of Dr Daniel Jolley’s (Staffordshire University) research has shown that a belief in, and exposure to, vaccination conspiracy theories reduce people’s hypothetical intentions to vaccinate a fictional child. ‘These effects mirror our work showing that conspiracy theories may encourage disengagement with politics and climate science, but also potentially inspire people to act in an unethical way.’

When I asked Jolley about the best approaches or interventions to tackle misinformed beliefs in conspiracy theories he said this was a ‘million dollar question’. ‘I have a paper that has looked into anti-vaccine conspiracy theories and we found that if a person is given anti-conspiracy material this seems to inoculate them against the conspiracy theory. However, if they are exposed to conspiracy theories first, the conspiracy account becomes enrooted in their belief system and can be somewhat resistant to correction. Conspiracy theories may, therefore, be quite “sticky”.’

Dr Sander van der Linden (University of Cambridge) has researched this idea of inoculation against misinformation within the areas of vaccination and climate change beliefs. While it may seem logical to simply debunk myths which surround vaccinations among those who believe them, the reality is less simple. The very act of repeating incorrect information in the act of debunking can reinforce the memory of this information, which is known as the continued influence effect.

‘The inoculation approach draws on the medical analogy,’ van der Linden explained. ‘Just as injecting someone with a weakened dose of a virus triggers antibodies in the immune system to help confer resistance against future infection, the same can be done with information: by exposing people to weakened doses of misinformation, or the strategies used in the production of misinformation, mental antibodies can be cultivated that help people from being persuaded by fake news in the future. We have shown this in a variety of studies and contexts. It is very much premised on the idea that prevention is better than cure, especially given what we know about the continued influence effect of misinformation. It is a proactive rather than reactive approach.’

Once a belief in vaccination myths is embedded there are other techniques which may also be more effective than simple debunking. ‘In prior research, we have found that rather than debunking a myth, just reinforcing the scientific consensus that over 90 per cent of doctors think that approved vaccines are safe and recommend that parents should be required to vaccinate their children, not only strengthens scientific beliefs about vaccines, but also reduces endorsement of the falsified autism-vaccine link.’

Another technique is to replace a myth with an alternative story. ‘Once something is debunked or retracted, it leaves a gap, which creates a problem for people in that our assessments of truth often require internal coherence (“well if the flu shot doesn’t cause the flu, how does it work?”). Accordingly, a simple correction doesn’t eliminate the continued influence effect. The correction needs to provide a compelling alternative story to fill the gap in people’s minds. What I mean by compelling is that it needs to be simple rather than too complex to understand and remember.’

A third approach is to appeal to social motivations among those who believe incorrect information about vaccines. ‘Some research shows that by explaining the concept of herd immunity, i.e. that vaccinating yourself and your children is actually helping to protect other members of the community who may not able to receive vaccinations themselves (e.g. elderly, other children), people become more willing to vaccinate. People often don’t think about the social consequences of their actions, so highlighting that if enough people are vaccinated in a community, herd immunity offers protection even to those who cannot get vaccinated, may help.

‘Vaccines are a classic social dilemma: if everyone gets vaccinated we are all better off than if no one vaccinates, in which case, we are all worse off. At the end of the day, it represents a psychological dilemma that is perhaps as old as humans themselves; when do we act in the interest of the collective?’ 

- To read a review of the factors which underlie vaccination-related behaviours, published in Psychological Science in the Public Interest, see

See also an unusual approach to increasing the effectiveness of vaccinations.

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