OPINION16 September 2021

How widespread is vaccine hesitancy?

Behavioural economics Covid-19 Opinion

Behavioural science techniques can help uncover the likely levels of Covid-19 vaccine take up, says Komal Shah.

Covid-19 vaccine

The global Covid-19 pandemic has had profound implications for individuals, businesses, and governments. A lot of hope and expectation rests on the success of the vaccine rollout to help return life to some degree of normality.

Almost 18 months ago, as many of us again shut our doors and stayed home, we placed our hope on the Covid-19 vaccines to help us return to normalcy. Between April and June 2020, intention to be vaccinated was strong, with more than 80% of people in the UK showing an inclination to be immunised should a vaccine become available.

Despite progress with vaccine rollout in the UK, fewer than 25% of the world’s population has been vaccinated, and emerging new variants, some of which show some resistance to the vaccine, means time is of the essence. Understanding how behaviour and attitudes towards vaccine uptake are changing could be crucial in navigating the final stages of the pandemic, as well as future public health measures.

Standard surveys that rely on people’s ability to introspect and honestly report their thoughts and actions often overlook the impact of behavioural biases. These respondents, just like all of us, are prone to overreporting intentions for behaviours that are socially desirable. Just think back to the year of 2016 – where the actual results of the US election and the EU referendum were contradictory to popular survey indicators.

To overcome these challenges, Swiss Re carried out behavioural science-led research to more accurately measure current attitudes around vaccine hesitancy and the underlying factors. Questions were carefully constructed with known behavioural biases in mind, such as the intention-action gap and ambiguity aversion.

What we discovered, was that at the time of conducting the research only 50% of respondents said that they would definitely get the vaccine – that is a much lower proportion than were willing to last year. In fact, four in 10 were undecided.

We believe the intention-action gap could be at play here. It refers to the difference between what people say that they would like to do and what they actually do. A large part of this is also temporal – for instance, it’s easier for me to say “I will start exercising next month” but fall short on my intention nearer the time.

When decision-making time is upon us, people may think more carefully about their original vaccination intention and how it impacts them. We have seen this play out in the UK, where more people have now taken the vaccine, despite being unsure previously.

On top of this, it’s likely that ambiguity aversion is playing a role. Us humans have a preference for certainty over ambiguity and tend to steer away from making decisions about uncertain outcomes. It’s probably fair to say that there are unknown risks and complex uncertainties – such as possible side effects or trusting a novel vaccine – in deciding whether to take the Covid-19 vaccine. In fact, more than 70% of our respondents cited potential side effects as the most endorsed reason for not getting vaccinated, illustrating how such unknowns can complicate decision-making.

Similarly, Dectech conducted research to predict the success of the vaccine rollout. A key variable is the public’s willingness to accept the vaccine. However, people often want to appear more socially desirable and tend to overstate such intentions and behaviour.

As such, Dectech used a technique called unmatched count which anonymises individual participant’s responses and thereby increases honesty. They found people are embarrassed to admit that they’ll refuse the vaccine, with only 24% saying they’ll reject it when asked directly compared with 36% when asked anonymously.

On the bright side, vaccine hesitancy is decreasing, with the underlying refusal rate dropping to 31% in January 2021 compared to the 36% seen in November 2020.

These research techniques enable us to gauge the true motivations of people, as best as possible, and can help drive impactful actions from corporates and governments.

Komal Shah is a behavioural science consultant for Swiss Re

Shah is speaking at the MRS Behavioural Science Summit 2021 later this month


[ 1 ] Thorneloe, R., Wilcockson, H. E., PhD, Lamb, M., Jordan, C. H., & Arden, M. ( 2020, July 20 ). Willingness to receive a Covid-19 vaccine among adults at high-risk of Covid-19: a UK-wide survey. https://doi.org/10.31234/osf.io/fs9wk

[ 2 ] WHO Coronavirus (Covid-19 ) Dashboard. https://covid19.who.int/

[ 3 ] Conner, M., & Godin, G. ( 2007 ). Temporal stability of behavioural intention as a moderator of intention-health behaviour relationships. Psychology & Health, 22( 8 ), 875-897. doi:10.1080/14768320601070449

[ 4 ] https://coronavirus.data.gov.uk/details/vaccinations

[ 5 ] COVID-19 vaccine confidence is growing, global survey suggests | Imperial News | Imperial College London

[ 6 ] Trautmann, S. T., Vieider, F. M., & Wakker, P. P. ( 2008 ). Causes of ambiguity aversion: Known versus unknown preferences. Journal of Risk and Uncertainty, 36( 3 ), 225-243

[ 7 ] Dectech research: https://www.dectech.co.uk/wp-content/uploads/2021/04/210222-Covid-19-Vaccine-Rollout-Report.pdf