• Atakan Erdogdu

Going From No to Yes: Utilizing Insights From Behavioural Science to Increase Vaccination Uptake

The COVID-19 pandemic is continuing at an increased pace to disrupt economic and societal order while imposing enormous burdens of morbidity and mortality. Although the newly developed vaccines by Pfizer & BioNTech, Moderna, and AstraZeneca are celebrated by many in anticipation of the eventual loosening of COVID’s grip on their lives, another subtle, yet profound, challenge remains to be resolved to go back to the new normal – mass vaccination.

Figure 1: Attitudes towards vaccination | Source: IPSOS, 2020, p.1.

Governments need not only to provide ready access to nationwide vaccination against COVID-19, but also to develop strategies that increase public confidence in and acceptance of the developed vaccines. Alas, in many countries, vaccine hesitancy, that is, the “delay in acceptance or refusal of vaccines despite availability of vaccination services” (WHO, 2020, p.1), manifest itself as a substantial obstacle to achieve community immunity that protects the whole population. Specifically, current levels of willingness to accept a COVID-19 vaccine are insufficient to meet the requirements to attain mass coverage in most of the countries surveyed worldwide. Globally, roughly one-third of people are either undecided or against vaccination, many of them indicating concerns about potential side-effects (Milkman, 2020 & Ipsos, 2020).

The situation is even direr in countries whereby there is a low level of trust in government and the public healthcare system – as trust plays an enormous role in the willingness to get vaccinated (Lazarus et al. 2020). As such, almost 50% of the Hungarian population do not have an either negative or positive stance towards vaccination, with people aged 18-24 being most likely to oppose the vaccine while people over 65 the most likely to accept, and only 14.9% of the population indicate their intent to get vaccinated (KSH, 2020). These, together with the significant decline between August 2020 and October 2020 in the number of people indicating that they will receive vaccination, suggest a challenge of behaviour change that can be overcome through the effective application of behavioural science, encouraging more people to do the right thing for both themselves and the society in general.

Vaccine Hesitancy Determinants: The 3C Model

Figure 2: Vaccine Hesitancy Determinants, simplified

As in many cases, showing why people do not behave as they should, can also shed light into, by implication, how to reorient mass behaviour. With regard to COVID-19 inoculation, overcoming vaccine hesitancy is an outcome behaviour that arises from the interaction of a multitude of factors that can potentially influence an individual’s decision to search for and get vaccination. Although many think that communicating the reasons for vaccination should suffice for an average individual to get vaccinated, vaccine hesitancy has numerous, context-specific root causes that are not knowledge related – the causes that are grouped as complacency, confidence, and convenience by the SAGE Working Group on Vaccine Hesitancy.

Complacency: Why do young adults not feel the need to get vaccinated?

Vaccination behaviour is traditionally viewed as an individual decision-making task whereby the risks of being unvaccinated are evaluated against the risks of the disease the vaccine prevents. Complacency occurs when there is a lack of perceived risk of the vaccine-preventable disease to the extent that vaccination is not regarded as a necessary preventive action by the decision-maker.

Figure 3: COVID-19 Mortality Rate by Age Group | Source: OurWorldinData, 2020

There exists a risk asymmetry between age groups for COVID-19 contraction. Whereas the mortality rate is between 0.2% and 0.4% for people aged below 50, the death rate is significantly higher – 3.6% in the 60-69 age bracket, 8% among those aged 70-79, and 14.8% for people aged 80 or more (Ourworldindata, 2020). Unpredictability of adverse reactions to the vaccines, together with the increased susceptibility to misinformation, lead people to exaggerate concerns about potential side effects, which are contingent and exotic and result in people perceiving the risks of getting vaccinated to be greater than they actually are, negatively affecting the willingness to get inoculated. Accordingly, vaccine-related events are perceived as man-made risks that can be avoided through bypassing inoculation, whereas COVID-19 contraction is perceived as a natural-risk that can only be avoided by taking that extra risk posed by the vaccines. Viewed through this lens, the low levels of intention to get vaccinated in young adults becomes a natural result due to the fact that the risks associated with vaccination outweigh those of not vaccination.

So how can behavioural science help to counteract this phenomenon? Every individual has something at stake in regard to the pandemic. For some it is their health, whereas for others it is their social lives that they want to protect and take back. However, what has been done hitherto has been unsatisfactory in the sense that the authorities have taken a one-size-fits-all approach to communicate the potential risks and benefits of not getting vaccinated. What matters the most for young adults is to continue their normal lives, and for this group, the benefits of vaccination, rather than the risks of not vaccinating should be communicated, establishing the causal link among vaccination, community immunity, and the new normal; thereby overcoming the lack of perceived risk via shifting the focus to benefits.

Confidence: The trust in the system

In almost every decision we make, trust is a key factor, and COVID-19 vaccination is no exception to this rule. Confidence comprises the “trust in the effectiveness and safety of vaccines, the system that delivers them, and the motivation of policy-makers who make vaccine decisions” (Macdonald & SAGE Group on Vaccine Hesitancy, 2015, p. 2). The most recent global survey found that high level of trust in the government was the most reliable determinant for vaccination intention, overshadowing population mortality, age, education, and even family sickness with COVID-19 (Lazarus et al., 2020). It is also interesting to observe that perceived safety of vaccines by the region is lowest in Eastern Europe (GallupWorldPoll, 2018). These might suggest that there exists an uncomfortable echoing of the past regimes and experiences, whereby individuals bring in their negative past experiences with government-related authorities whilst evaluating the information that emanate from them. But it is notable that anti-vaxxer groups gain support as well, a global trend which is also observable in the surrounding countries. In addition, the widespread concerns about lack of due diligence in developing the vaccines further exacerbate the problem by decreasing the intention to get vaccinated.

Behavioural science suggests that the value of information depends on the source of it. Evidence shows that people look to their peers for hints about how to behave. To reach specific target groups, community leaders in social circles can act as messengers. In addition, providing tangible, social cues, such as ‘I received vaccination’ stickers can and will not only instil a new social norm of getting vaccinated but also address the fears and concerns about safety, increasing the intention to get inoculated. However, governments and health authorities should also be proactive to turn over the problem by addressing the widespread concerns publicly. It is equally important not to become aggressive with communicating, as it might scare away those who are hesitant. In short – information flow and communication should be consistent, reassuring, adequate in its content, but not overused, and should always come from a person with authority and of reputation.

Convenience: When intention does not follow action

When people make decisions, despite the inner intention they possess, seemingly small factors hinder their ability and desire to follow-through. Apropos of COVID-19, convenience captures the potential negative effects of physical availability, hassle factors (e.g. paperwork), required mental effort, affordability, and time on the vaccination decision. In this case, affordability and availability do not appear to be important considerations, except for developing countries. Yet, given that to get the sufficient number of antibodies people need to receive two inoculations several weeks apart, possible adverse experiences with the initial shot, together with people’s tendency to forget, postpone, and change their decisions can negatively affect the desired vaccination behaviour.

Luckily, behavioural science has proved to be highly effective in bridging the gap between intention and action. Previous randomized experiments reveal that even the simplest techniques such as sending a reminder to individuals about their upcoming appointment increased vaccination by 36% (Chapman et al, 2010). Providing flexible options to people and accounting for their tendency to forget also proved to be highly effective. After all, it all boils down to understanding people and creating the most convenient ways to follow their intention, sometimes giving them a nudge in the back by sending them clear guidelines and reminders. Communicating these guidelines in a simple, yet memorable way can also help – in the case of the BioNTech-Pfizer vaccine, communicating the recommended 3-week interval can be highly effective.

Looking Ahead

The existing prevalence of wide variation – both in sociodemographic and health characteristics in willingness to accept vaccination delays not only the elimination of the pandemic but also the expected societal and economic recovery. According to the experts, between 60-80% of the population needs to get vaccinated to overcome the pandemic (Fox et al., 2020). Yet, with one-third of people being hesitant or rejecting vaccination, there remains a significant gap to reach the goal and to attain herd immunity. The increased susceptibility to misinformation, lack of perceived risk in certain age groups, mistrust in the government and healthcare system, and exaggerated concerns about the side effects of vaccines further exacerbate the problem. The insights of behavioural science, through pinpointing the most effective messenger channels that guide behaviour, instilling trust within the healthcare system, and nudging people to follow-through with their intentions, would be of seminal importance in developing a new conceptualization of vaccination for hesitant subgroups and to bring the pandemic to an end.

Since the beginning of the pandemic, 4883 people, on average, have lost their lives each day due to COVID-19. The potential to save lives has never been higher before. Yet, this potential can only be achieved if there is a mass behaviour change, for which, the insights of behavioural science would be critical to obtain community immunity in the shortest period of time. It is vaccination, not vaccines by themselves, that saves lives.


Chapman, B. G., Li, M., Colby, H. and Yoon, H. (2010). Opting in vs Opting out of influenza vaccination. JAMA The Journal of the American Medical Association, 304(1), pp. 43-44.

Fox, J. S., Potu, P., Lachmann, M. Srinivasan, R. and Meyers, A. L. (2020). The COVID-19 herd immunity threshold is not low: A re-analysis of European data from spring 2020. MedRxiv. doi: 10.1101/2020.12.01.20242289

GallupWorldPoll. (2018). Attitudes to vaccines [Online]. Available at:

IPSOS. (2020). COVID-19 vaccination intent is decreasing globally [Online]. Available at:

KSH. (2020). HSCO Weekly Monitor [Online]. Available at:

Lazarus, V. J., Ratzan, C. S., Palayew, A., Gostin, O. L., Larson, J. H., Rabin, K., Kimball, S. and El-Mohandes, A. (2020). A global survey of potential acceptance of a COVID-19 vaccine. Nature Medicine. doi: /10.1038/s41591-020-1124-9.

Macdonald, E. N. and the SAGE Working Group. (2015). Vaccine Hesitancy: Definition, scope, and determinants. Vaccine, 33(34), pp. 4161-4164.

Milkman, K. (2020). Katy Milkman on how to nudge people to accept a COVID-19 vaccine. The Economist [Online]. Available at:

OurWorldInData. (2020). Statistics and Research: Coronavirus Pandemic [Online]. Available at:

WHO. (2020). Vaccine Hesitancy: what it means and what we need to know in order to tackle it [Online]. Available at:

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