Vaccination in times of pandemic

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Olivier Chanel and Stéphane Luchini share their views and research results on the economics of epidemics, testing, health.

If we want to stop the COVID-19 pandemic, we’ll need to acquire herd immunity (i.e. about 70% population coverage). This can be achieved through natural infection via contact with infected people (but it is not certain that this will protect people, especially those who have only been a vector) and/or through a mass vaccination campaign once a vaccine is available.

However, because compulsory vaccination is hard to imagine in modern democracies, governments need to convince the targeted populations to subscribe to the recommendations of health authorities through efficient and persuasive information campaigns. Economic theory suggests that since vaccination campaigns may be plagued by an externality problem, people do not take into account the positive effect their vaccination has on others and a type of prisoner dilemma arises.

Ten years ago, the 2009 swine flu (H1N1) pandemic demonstrated that the public’s support is essential for the success of a vaccination campaign. In total, instead of the targeted 75%, less than 9% of the French population was vaccinated (as in Germany, Italy, the United Kingdom, Belgium, China or Mexico, for example). Luckily, the consequences were mainly financial, since swine flu was less severe than a seasonal flu (partly because people over 60 benefited from immunity acquired during the 1957–58 influenza pandemic). But COVID-19 is a different story because the health stakes are higher.


An experiment conducted in December 2009 (which marked the first epidemic peak in France and the beginning of the vaccination campaign) to examine how different types of information can influence individual vaccination decisions may provide some interesting insights. We proposed an interactive one-hour experimental session to 175 general public participants, with immediate feedback via an electronic voting system recording participants’ choices in real time. Intentions to vaccinate were elicited five times, a different type of information (the results of the votes) being provided before each elicitation. In step 1, initial intentions were based on the prior stock of information and experience of participants. Subsequent information concerned others’ intentions regarding vaccination (step 2), public opinion about a swine flu vaccination campaign (2 positive and 2 negative slants, step 3), others’ beliefs about a swine flu pandemic (2 quantitative subjective belief questions, step 4) and quantitative scientific information provided through experts (a 25-minute interactive round table with two renowned health academics, step 5).


Initial intentions were found to increase with previous vaccination against flu, good self-assessed health status, positive attitude toward vaccination in general, high self-estimated level of knowledge about vaccination and using health professionals as information source. Intentions were found to decrease with being a female and consulting Internet for information. Participants did not react to the information provided in stage 2 about other participants’ low level of intentions to vaccinate, which confirms that they were not thinking strategically (not “free-riding” on others’ vaccinations). We also found that formulating opinions about the vaccination campaign (stage 3) and beliefs about the risk of contamination (stage 4) did not influence intentions to vaccinate, even when feedback about other people’s opinions was provided. This means that participants did not use the information provided by the feedback on others’ behaviours and opinions. In the end, it was the scientific information provided in stage 5 that proved crucial, leading to a positive change in intentions to vaccinate. Overall, these results show that the individual attitude to vaccination is based on personal appraisal of the situation. Providing scientific information can help health authorities bring the public’s willingness to vaccinate into line with optimal vaccination coverage.


How can scientific information be propagated in the best and most practical way? Clearly, the conditions of stage 5 are difficult to replicate for a sizeable segment of the population during a pandemic, especially under the prevailing social distancing. A successful information channel needs to guarantee that people trust the information provided. Traditional media and Internet seem to be poor candidates: we found that people informed by these media rather than by medical professionals were less provaccination. Two directions for optimal mass media communication of credible scientific information in addition to the family doctor seem possible. The first is healthcare websites provided by health practitioners, which offer an arena for constructive debates informing the public about health issues and public health interventions. The second is television broadcasts that present relevant objective health data, organise debates among health specialists and allow interactivity with viewers through telephone, SMS, Internet and surveys.


Chanel O., Luchini S., Massoni S., Vergnaud J-C., «Impact of information on intentions to vaccinate in a potential epidemic: Swine-origin Influenza A (H1N1)» Social Science & Medicine, 72-2, 142-148.


→ This article was issued in AMSE Newletter, Spring 2020 - Special edition on Covid-19 Crisis


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