Vaccination, Herd Behavior, and Herd Immunity (original) (raw)

Decision to Get Influenza Vaccination: A Behavioral Economic Approach

2009

The aims of this study were to identify predictors regarding people fs willingness to be vaccinated against influenza and to determine how to improve the inoculation rate using our original large-scale survey in the USA in 2005. The main results are (a) a model of bounded rationality explains vaccination behavior fairly well, i.e., people evaluate the costs and benefits of vaccination by applying risk aversion and time preference, while the estatus quo bias f of those who received vaccinations in the past affect their decision to be vaccinated in the future, (b) it is recommended to increase people fs knowledge regarding flu vaccination, but not regarding influenza illness, (c) reducing the vaccination fee may be ineffective in raising the rate of vaccination.

A policy to promote influenza vaccination: A behavioral economic approach

Health Policy, 2010

The aims of this study were to identify the predictors of people's willingness to be vaccinated against influenza and to determine how to improve the inoculation rate. The study was based upon the results of our original large-scale survey conducted in the USA in 2005. A model of bounded rationality can explain vaccination behavior fairly well: (a) people evaluate the costs and benefits of vaccination by applying risk aversion and time preference; (b) the 'status quo bias' of those who were vaccinated in the past affects their decision to be vaccinated in the future; and (c) overconfidence indirectly affects the decision through the moderation of perceived variables. Policy implications include: (a) dissemination of information about the vaccine is especially important among people who are inexperienced with the vaccine since they undervalue the effectiveness of vaccination; (b) lowering the total cost of vaccination, including time costs (for example, by offering the vaccine at workplaces) may raise the inoculation rate, especially among those inexperienced with the vaccine, since those who have experience with the vaccine tend to take it on a regular basis.

“Wait and see” vaccinating behaviour during a pandemic: A game theoretic analysis

Vaccine, 2011

During the 2009 H1N1 pandemic, many individuals did not seek vaccination immediately but rather decided to "wait and see" until further information was available on vaccination costs. This behaviour implies two sources of strategic interaction: as more individuals become vaccinated, both the perceived vaccination cost and the probability that susceptible individuals become infected decline. Here we analyze the outcome of these two strategic interactions by combining game theory with a disease transmission model during an outbreak of a novel influenza strain. The model exhibits a "wait and see" Nash equilibrium strategy, with vaccine delayers relying on herd immunity and vaccine safety information generated by early vaccinators. This strategic behaviour causes the timing of the epidemic peak to be strongly conserved across a broad range of plausible transmission rates, in contrast to models without such adaptive behaviour. The model exhibits not only feedback mechanisms but also a feed-forward mechanism: a high initial perceived vaccination cost perpetuates high perceived vaccine costs (and lower vaccine coverage) throughout the remainder of the outbreak. This suggests that any effect of risk communication at the start of a pandemic outbreak will be amplified compared to the same amount of risk communication effort distributed throughout the outbreak.

Free-Riding Behavior in Vaccination Decisions: An Experimental Study

PLoS ONE, 2014

Individual decision-making regarding vaccination may be affected by the vaccination choices of others. As vaccination produces externalities reducing transmission of a disease, it can provide an incentive for individuals to be free-riders who benefit from the vaccination of others while avoiding the cost of vaccination. This study examined an individual's decision about vaccination in a group setting for a hypothetical disease that is called ''influenza'' using a computerized experimental game. In the game, interactions with others are allowed. We found that higher observed vaccination rate within the group during the previous round of the game decreased the likelihood of an individual's vaccination acceptance, indicating the existence of free-riding behavior. The free-riding behavior was observed regardless of parameter conditions on the characteristics of the influenza and vaccine. We also found that other predictors of vaccination uptake included an individual's own influenza exposure in previous rounds increasing the likelihood of vaccination acceptance, consistent with existing empirical studies. Influenza prevalence among other group members during the previous round did not have a statistically significant effect on vaccination acceptance in the current round once vaccination rate in the previous round was controlled for.

Using Game Theory to Examine Incentives in Influenza Vaccination Behavior

Psychological Science, 2012

The social good often depends on the altruistic behavior of specific individuals. For example, epidemiological studies of influenza indicate that elderly individuals, who face the highest mortality risk, are best protected by vaccination of young individuals, who contribute most to disease transmission. To examine the conditions under which young people would get vaccinated to protect elderly people, we conducted a game-theory experiment that mirrored real-world influenza transmission, with "young" players contributing more than "elderly" players to herd immunity. Participants could spend points to get vaccinated and reduce the risk of influenza. When players were paid according to individual point totals, more elderly than young players got vaccinated, a finding consistent with the Nash equilibrium predicting self-interested behavior. When players were paid according to group point totals, however, more young than elderly players got vaccinated-a finding consistent with the utilitarian equilibrium predicting group-optimal behavior-which resulted in higher point totals than when players were paid for their individual totals. Thus, payout structure affected whether individuals got vaccinated for self-interest or group benefit.

Impact of information on intentions to vaccinate in a potential epidemic: Swine-origin Influenza A (H1N1)

Social Science & Medicine, 2011

Vaccination campaigns to prevent the spread of epidemics are successful only if the targeted populations subscribe to the recommendations of health authorities. However, because compulsory vaccination is hardly conceivable in modern democracies, governments need to convince their populations through efficient and persuasive information campaigns. In the context of the swine-origin A (H1N1) 2009 pandemic, we use an interactive study among the general public in the South of France, with 175 participants, to explore what type of information can induce change in vaccination intentions at both aggregate and individual levels. We find that individual attitudes to vaccination are based on rational appraisal of the situation, and that it is information of a purely scientific nature that has the only significant positive effect on intention to vaccinate. Résumé Les campagnes de vaccination pour prévenir de la propagation d'épidémies ne peuvent réussir que si les populations ciblées acceptent de souscrire aux recommandations des autorités sanitaires. Cependant, comme la vaccination obligatoire est difficilement concevable dans les démocraties modernes, les gouvernements doivent persuader leurs populations à travers des campagnes d'information efficace et convaincante. Dans le cadre de la grippe A de 2009, nous utilisons une étude interactive menée auprès de 175 participants dans le Sud de la France, afin d'explorer quel type d'information peut induire un changement dans les intentions de vaccination à la fois au niveau agrégé et au niveau individuel. Nous constatons que les attitudes individuelles face à la vaccination sont basées sur une évaluation rationnelle de la situation, et que ce sont des renseignements de nature purement scientifique qui sont les seuls à avoir un effet significativement positif sur 'intention de vacciner.

Chapman, G.B., Li, M., Vietri, J.T., Ibuka, Y., Thomas, D., Yoon, H. & Galvani, A. (2012). Using game theory to examine incentives in influenza vaccination behavior. Psychl Science

The social good often depends on the altruistic behavior of specific individuals. For example, epidemiological studies of influenza indicate that elderly individuals, who face the highest mortality risk, are best protected by vaccination of young individuals, who contribute most to disease transmission. To examine the conditions under which young people would get vaccinated to protect elderly people, we conducted a game-theory experiment that mirrored real-world influenza transmission, with "young" players contributing more than "elderly" players to herd immunity. Participants could spend points to get vaccinated and reduce the risk of influenza. When players were paid according to individual point totals, more elderly than young players got vaccinated, a finding consistent with the Nash equilibrium predicting self-interested behavior. When players were paid according to group point totals, however, more young than elderly players got vaccinated-a finding consistent with the utilitarian equilibrium predicting group-optimal behavior-which resulted in higher point totals than when players were paid for their individual totals. Thus, payout structure affected whether individuals got vaccinated for self-interest or group benefit.

Ibuka, Y., Li, M., Vietri, J., Chapman, G.B. & Galvani, A.P. (2014) Free-riding behavior in vaccination decisions: an experimental study. PLOS one

Individual decision-making regarding vaccination may be affected by the vaccination choices of others. As vaccination produces externalities reducing transmission of a disease, it can provide an incentive for individuals to be free-riders who benefit from the vaccination of others while avoiding the cost of vaccination. This study examined an individual's decision about vaccination in a group setting for a hypothetical disease that is called ''influenza'' using a computerized experimental game. In the game, interactions with others are allowed. We found that higher observed vaccination rate within the group during the previous round of the game decreased the likelihood of an individual's vaccination acceptance, indicating the existence of free-riding behavior. The free-riding behavior was observed regardless of parameter conditions on the characteristics of the influenza and vaccine. We also found that other predictors of vaccination uptake included an individual's own influenza exposure in previous rounds increasing the likelihood of vaccination acceptance, consistent with existing empirical studies. Influenza prevalence among other group members during the previous round did not have a statistically significant effect on vaccination acceptance in the current round once vaccination rate in the previous round was controlled for.

Vaccine uptake and constrained decision making: The case of Covid-19

Social Science & Medicine, 2021

Policy makers require support in conceptualizing and assessing the impact that vaccination policies can have on the proportion of the population being vaccinated against COVID-19. To this purpose, we propose a behavioural economics-based framework to model vaccination choices. We calibrate our model using up-to-date surveys on people attitudes toward vaccination as well as estimates of COVID-19 infection and mortality rates and vaccine efficacy for the UK population. Our findings show that vaccine campaigns hardly reach herd immunity if the sceptics have real-time information on the proportion of the population being vaccinated and the negationists do not change their attitudes toward vaccination. Based on our results, we discuss the main implications of the model's application in the context of nudging and voluntariness versus mandatory rule-based policies.