Behavioural consequences of vaccination recommendations: An experimental analysis.

Annual vaccination is the most effective way to prevent seasonal influenza. However, globally, the recommendations vary from country to country, ranging from universal recommendations, risk-group-specific recommendations, to no recommendation at all. Due to high diversity both in recommendation practice and country-specific preconditions, it is difficult to determine the effect of different recommendations on vaccine uptake. This incentivised laboratory experiment (N = 288) tests the behavioural consequences of different recommendations in a repeated interactive vaccination game. The participants are part of heterogeneous groups, comprised of low- and high-risk type of players. They receive either a universal, risk-group-specific or no recommendation prior to their vaccination decisions. Results show that individuals are sensitive to the recommendations. In detail, a risk-group-specific recommendation increases vaccine uptake of high-risk types. However, at the same time, it decreases vaccine uptake of low-risk types. The results imply that when the proportion of low-risk types in a population is considerably larger than the high-risk group, a risk-group-specific (vs. universal) recommendation comes at the cost of decreased social benefit of vaccination due to the overall lower vaccine uptake. Policy decision-making should therefore complement epidemiological considerations with potential positive and negative behavioural consequences of vaccination recommendations.