An insight into our decision-making process….when it comes to vaccination.

Based on on ref. 1 and on the plenary talk of Gregory Polanda at the World Vaccine Congress in Barcelona, Spain (October 2022).

a: Director of Mayo Clinic Vaccine Research Group, Mayo Clinic, Rochester, MN, USA

  While attending the World Vaccine Congress in Barcelona this past October, I particularly enjoyed the plenary talk by Gregory Poland, MD and Director of the Mayo Clinic Vaccine Research Group (Mayo Clinic, Rochester, MN, USA). The talk was a very well-rounded and well-referenced presentation of the non-scientific, non-evidence based factors that come into play in our decision-making process. In this case, referring to our decision to get vaccinated against SARS-CoV2, or not.

  One of the most striking aspects of the SARS-CoV2 pandemic has been the reluctance, or even further, the unwillingness, of the people to get vaccinated, despite the demonstrated gravity of the health, social and economic impact this health crisis has had from the very beginning (1). The actual term for this human behaviour is vaccine hesitancy, and it is not new. It refers to the unwillingness of an individual to receive vaccination, once the vaccines have been recommended by the official authorities and made available to the local communities. Most importantly, in 2019 the WHO classed vaccine hesitancy as one of the top ten threats to global health (2). This attitude results largely from ignorance, mistrust as well as mis- and dis-information (1, 3).

Human decision-making: the result of physiological, psychological and broader context factors.

  While communication strategies around vaccination have been using, up to present, an analytical approach (data-based) with the idea that uniform and consistent communication should be enough for convincing people on the necessity of getting vaccinated, the observed human reactions indicate that this strategy is neither sufficient nor effective enough. Human decision-making seems to strongly reside on beliefs. And beliefs are very often pre-formed by the context we live in, long before we need to explain or justify them rationally. In fact, beliefs come first, explanations follow (4). It has become increasingly clear that, in order to optimise people’s acceptance of vaccination programmes, a multidisciplinary approach is needed; one that will take into account factors such as (i) the physiology of our brain, especially under conditions of stress and uncertainty, (ii) our psychology, including our individual cognitive styles, and (iii) our broader context (religious, socio-economic, political). That is a lot to take in, you may think… Let us break this down to some key ideas.

The human brain in fear

  The human brain physiology switches mode of function when the environmental cues indicate it is necessary. That is to say, under conditions of anxiety and threat perception our brain switches to fight-or-flight mode, using the sympathetic nervous system. The amygdala is engaged and our executive and decision-making function are shut down, or let ‘s just say are very limited (1).It all comes from a long history of evolving to survive! Taking into account the neurobiology of fearis key for understanding thestate many people may find themselves in, during a pandemic situation. Experiencing prolonged uncertainty or repeated trauma may cause an individual to switch to a more long-term use of amygdala-based reactions. These principles, among others, highlight why it is important to have available guidelines in advance, as part of preparedness protocols and pandemic planning, rather than have to devise them upon the outbreak of a pandemic, which favours on-the-spot decision-making (in fight-or flight mode, rather than using the prefrontal cortex).


Our psychology and cognitive style

  Despite the survival mode our brain switches to, it seems we humans have a tendency to overestimate our decision-making skills, even under conditions of uncertainty. It does not come as a shock, therefore, to discover that we fall victims of all sorts of biases and heuristics, as shown by studies spanning decades (5). Two main lines of processing, System I vs System II, are thought to be involved into our decision-making, as defined by Daniel Kahneman, Professor of Psychology (Nobel Prize 2002) (6). System I takes the quick-and-dirty approach and allows us to make rapid, automatic decisions in everyday life. It is very useful for managing simple tasks, yet it is prone to thinking errors. System II, on the contrary, follows a path of conscious thinking with the more analytical, as well as laborious, features this comes with. While System II can override thinking errors, it is also slow and lazy (!), explaining why we do not always activate it! Coming back to the fight-or-flight mode, System I is more likely to dominate in circumstances of anxiety.

  As if this was not enough, cognitive styles add to the bias of our decisions; the availability vs the confirmation bias (7, 8)! The first one describes the human tendency to grab the first piece of information that comes to mind (that is available to us) and use it as evidence or as an argument for a case (to assess the likelihood of something happening, for example). The second refers to our tendency to retain the information (or theory, or line of thinking) that validates our initial pre-conception or conviction on a topic! Do you recognise some part of yourself in this? I hate to admit that I do. It seems, however, that we all fall for these mind traps, it is not to be taken personally. On top of it all, it is interesting to see that a negative side effect resulting from lack of action (omission) on an individual’s side is better-received by the individual and perceived as less threatening, as opposed to a negative effect resulting from an active decision (commission) made on their side. In other words, someone may be more comfortable with a side effect resulting from contracting SARS-CoV2 (it just happened, they took no conscious action), compared to a negative effect resulting from a vaccine against the virus that they actively chose to get. Individuals tend to fear commission. Could this be because it comes with a stronger sense of responsibility? And why, I would ask as devil’s advocate, do we not consider ourselves equally responsible for the things we do not do?  The situation of omission is another example in which System 1 thinking dominates, while the effort needed to override the thinking error results in System 2 failing.

All the rest: our environment

  As stated right from the start, our environment (cultural, socio-economic and political) weighs more that we may think or would like to acknowledge. Whether you are very attached to your family and friends, whether you are  the bandwagon-er type (going where everyone is going) or whether you flirt with conspiracy theories out of mistrust towards authority, one way or another, our milieu influences positively and negatively our decisions. Communities have always been very important for human existence and, when it comes to a pandemic, have an important role to play as a context within which discussions about healthcare should be happening, and are more likely to be impactful. Key figures within communities (from priests, to barbers (yes!) to any central figure basking in the trust of the community) can act as messengers and be part of the healthcare communication strategy. As an example, there has been an incentive in the U.S. for promoting healthcare training at the community level for barbers and beauticians, with the objective of increasing the vaccination rate of the African American population (9). A trusted member of the community can do much more for conveying a message than a factual evidence-based impersonal message. At the political level, the trust people feel towards their government (not only in the specific party, but in the political system as a whole) is strongly linked to their willingness to follow recommendations given by that government. The case of Denmark offers a positive example of trust in the government, translated in a spectacular rate of vaccination against SARS-CoV2 (10). On the contrary, the low percentage of vaccination, observed within minorities in the U.S., has been linked to mistrust of the government, related to past abuse of trust or misconduct, and constitutes a major factor leading to vaccination hesitancy (11, 12).

Re-designing the preparedness and pandemic response strategies

  Why is all the above analysis important? It is not necessarily about new principles or ideas that are unheard-of. No. The key concept is that understanding the state of mind (and soul) of the people we disagree with, allows us to be more empathetic towards them and therefore, to adjust accordingly the way we communicate our ideas to them. Human centered design (HCD) of communication strategies around vaccination aims to use emotional intelligence (empathy is part of it) in order to understand the needs, even the unspoken ones, underlying a person’s behaviour. Using a systems approach, HCD addresses the individual, within their environment (including the values, concerns and influences of the individual), when thinking of how best to communicate a message. Altogether, the parameters presented here provide food-for-thought when designing healthcare communication strategies, while highlighting even more the importance of planning for pandemic preparedness at the local and global level.

Text by Semeli Platsaki, PhD



1. Poland C. M., Ratishvilib T., and Poland G. A. 2022. Distorted human decision-making as a critical aspect of pandemic planning and preparedness. Yale Journal of Biology and Medicine, 95 281-92

2. WHO. Ten threats to global health in 2019. 2019. Available from: https://www.who.int/news-room/spotlight/ten-threats-to-global-health-in-2019

3. van der Linden S., Dixon G., Clarke C., Cook J. 2021. Inoculating against COVID-19 vaccine misinformation. EClinicalMedicine 33: 100772 https://doi.org/10.1016/j.eclinm.2021.100772

4. Shermer M. 2011. The believing brain: from ghosts and gods to politics and conspiracies-how we construct beliefs and reinforce them as truths. New York: Times Books

5. Poland C. M., Poland G. A. 2011. Vaccine education spectrum disorder: the importance of incorporating psychological and cognitive models into vaccine education. Vaccine 29 (37): 6145–8 DOI: 10.1016/j.vaccine.2011.07.131

6. Kahneman D. 2011. Thinking, Fast and Slow. Farrar, Straus and Giroux, New York

7. Mamede S., van Gog T., van den Berge K., Rikers R. M., van Saase J. L., van Guldener C., et al. 2010. Effect of availability bias and reflective reasoning on diagnostic accuracy among internal medicine residents. JAMA 304 (11): 1198– 203 DOI: 10.1001/jama.2010.1276

8. Zhao H., Fu S., Chen X. 2020. Promoting users’ intention to share online health articles on social media: the role of confirmation bias. Inf Process Manage 57 (6): 102354 DOI: 10.1016/j.ipm.2020.102354

9. Bugos C. 2021. Initiative Leverages Barbershops to Increase Vaccination Among Black Americans: Verywell Health Coronavirus News; Available from: https://www.verywellhealth.com/initiative-leverages-barbershops-to-increase-vaccination-among-black-americans-5188686

10. Petersen MB. 2021. COVID lesson: trust the public with hard truths. Nature 598 (7880): 237

11. Warren RC, Forrow L, Hodge DA Sr, Truog RD. 2020. Trustworthiness before Trust - Covid-19 Vaccine Trials and the Black Community. N Engl J Med. 383 (22): e121 DOI: 10.1056/NEJMp2030033

12. Corbie-Smith G, Thomas SB, St George DM. Distrust, race, and research. Arch Intern Med. 2002 162 (21): 2458–63 DOI: 10.1001/archinte.162.21.2458



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