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  • 28th Apr 2021

How can we use behavioural science to promote vaccination against COVID-19 in Latin America?

Results of two online experiments with Spanish-speaking populations

This blog is also available in Spanish.

On World Immunization Week, we want to share some of the learnings from our work promoting vaccination against COVID-19. For example, in Colombia, we found that a simple reciprocity message increased vaccination intent by 15% among the most skeptical population. We estimate that if these messages were sent to the entire adult population of Colombia and these intentions were translated into actions, these messages would lead to an additional 2.4 million Colombians being vaccinated.

In both Latin America and among Spanish-speakers in the United States, three out of ten people are unsure whether they will be vaccinated against COVID-19. 

The decision to get vaccinated (or to not get vaccinated) depends on many factors that vary according to each person and their context. Although there are structural barriers – such as the acquisition and distribution of vaccines, many barriers to vaccination are behavioural. For example, people are prone to overestimate the probability of unlikely events such as, in the case of vaccines, suffering a rare side effect.

To address some of these behavioural barriers, we created a series of messages with the goal of increasing confidence and intention to vaccinate against COVID-19 within the Spanish-speaking population in the United States and Colombia. The design of the messages was based on a literature review on how we can use behavioural sciences to promote vaccination, 15 focus groups (in Spanish and English), and the work of our COVID-19 team. 

What did we do?

Through our Predictiv platform we were able to access a representative sample of more than 1,700 Spanish-speaking participants in the United States, and of almost 2,700 participants in Colombia. Participants in our experiments were randomly assigned to view either 1 of 4 behaviorally informed messages or no message, as shown in the diagram below.

The messages combined behavioural elements such as:

  • Messenger effect – Appealing to high levels of trust in medical personnel and the potential impact of public figures on health issues on trust;
  • Building trust – To counteract people’s concern about the speed with which the vaccine was developed (a concern identified in survey data and systematic reviews) we generated a trust-building message which aimed to reassure using facts about the safety of the vaccine;

  • Reciprocity – Inspired by the work of UPenn academics who found that a reciprocity message increased flu vaccinations by 11%.

What did we find?

In both cases, we found that participants’ intention to get vaccinated was higher than the data we consulted before the experiments suggested. In Colombia, only 16% of respondents indicated an unwillingness to vaccinate against COVID-19. In both countries, younger people and women tended to be most hesitant to vaccinate compared to other groups. 

All messages were effective in increasing intent to vaccinate

All four behaviourally informed messages were effective in both countries. In Colombia, three out of four treatment messages showed a statistically significant difference when compared to not receiving a message. The most effective message combined confidence in healthcare professionals with the concept of reciprocity. We estimate that if these messages were sent to the entire adult population of Colombia, and intention translated into action, these messages could lead to an additional 2.4 million Colombians receiving the vaccine. 

In Colombia, all four messages were successful in increasing the intention to vaccinate. Three out of four treatment messages showed a statistically significant difference when compared to not receiving a message. The most effective message combined confidence in healthcare professionals with the concept of reciprocity. We estimate that if these messages were sent to the entire adult population of Colombia, and intention translated into action, these messages could lead to an additional 2.4 million Colombians receiving the vaccine.

High degree of fear to side effects

In Colombia, despite the intention to vaccinate rate being over 80%, 82% of our sample reported being concerned about side effects. Concerns about side effects were also a recurring theme in our focus group with US Spanish speakers, especially the fear that side effects may be severe for people with comorbidities such as diabetes. Fear of side effects was the main reasoning cited by those who did not intend to get vaccinated against COVID-19. 

People intend to socialize more after getting vaccinated

Another important finding was that people intend to continue following preventive measures (social distancing, hand washing, and/or mask wearing) after getting vaccinated. However, nearly all participants mentioned that they will be socializing more once they receive a vaccine. 

Importance of personalizing messages for their given context

We know it is important for each intervention to be adapted to its context, as efficacy can vary from one place to another. Through our exploratory research, we validated all messages (as well as the behavioural insights underpinning each) for use in each country. Further, by rigorously evaluating the messages with representative samples in the United States and in Colombia, we observed how highly similar messages can yield different results depending on their context. For example, the message focused on confidence towards healthcare staff and reciprocity had the best performance in Colombia.

Conclusion

These and other experiments show how behavioural science can contribute to increasing vaccination intentions and other preventive behaviours. Effective and equitable distribution of vaccines is vital to guarantee that these intentions can translate into actions. While vaccination rates have increased notably in the United States over the last few months, vaccination rates continue to be low across most of Latin America and the Caribbean. 

Governments in this region are facing the enormous challenge of receiving, safeguarding, distributing, and applying scarce vaccines in a simple, quick, and effective way. One of the main barriers to large scale vaccination is the limited availability of vaccines, a consequence of inequality in global distribution.  

As long as governments do not have the necessary doses to increase vaccination rates, maintaining compliance with preventive measures is critical. The work we have been doing over the past year has shown that behavioural science can have a major impact on promoting behaviours such as mask wearing or keeping social distance. In the coming months, we will be looking to continue working with government partners across the continent, both in promoting vaccination and maintaining compliance with preventive measures, to help in addressing an unprecedented challenge. 

Authors

Read more of our COVID-19 work