Vaccine views distorted by what people would like to be true, research finds

• People’s opinions about scientific knowledge are influenced by what people would like to be true, according to a study of UK attitudes to COVID-19 vaccinations
• Individuals were found to view ‘their’ vaccine as safer and more effective than alternatives – even despite what they may have previously stated
• Findings are published today (Wednesday) in the Journal of Health Economics

A study of the UK population’s attitudes towards COVID-19 vaccines has revealed how psychological factors can distort opinions about scientific facts.

New research, published today (Wednesday) in the Journal of Health Economics, tracked how a sample of 856 UK residents viewed the Pfizer and Moderna jabs both before and after their vaccination.

The vaccination policy in the UK, which did not allow patients to choose the type of their vaccine, provided researchers with a rare real-world opportunity for a natural experiment to study the dynamics of memory and beliefs in a personal health context.

Individuals were asked for their opinions of both the safety and effectiveness of both vaccines, as well as – if given the choice – whether they would choose a Pfizer or Moderna dose.

They found that, on average, individuals viewed ‘their’ vaccine as far better than they used to think, both in terms of its safety and its effectiveness.

There was also a trend for people to misremember their previously-stated beliefs, tending to believe that they thought well of their own vaccine all along, and would have chosen it if they could: even if they had previously stated a different preference.

Researchers believe that this uptick in optimism can be explained by a combination of motivated reasoning (where the desire to achieve a certain conclusion impacts our support of evidence), and humans’ tendency to overvalue events which are poorly informative (like one’s own experience with vaccination).

The findings shows that people tend to display retrospective optimism. Revising one’s own memories and opinions can protect individuals’ wellbeing by reducing fear and anxiety, especially given the irreversible nature of vaccine injection.

A previous study at the Wellbeing Research Centre found a similar form of retrospective optimism also using happiness measures.

Dr Alberto Prati, Ajinomoto Research Fellow at the University of Oxford’s Wellbeing Research Centre, Assistant Professor in Economics at the University College London, and co-author of the study, said:

“I think we helped uncover the roots of why people disagree. When people developed different hopes for what the scientific truth is, they ended up disagreeing about it. This shows that disagreement is more than a simple matter of different amounts of knowledge.”

Dr Charlotte Saucet, Assistant Professor of Economics at the University of Paris 1 Panthéon-Sorbonne, and co-author for the study, said:

“This study teaches us that beliefs are very adaptive. They change as a function of humans’ needs and desires. In real life, it is quite rare to have situations that allow to observe this phenomenon as neatly as during the COVID-19 pandemic in the UK.”

‘The causal effect of a health treatment on beliefs, stated preferences and memories’ is published in the Journal of Health Economics.

Image: Andrew Parsons / No 10 Downing Street, reproduced under license CC BY 2.0 DEED.