13. Economic and Behavioral Factors in an Individual’s Decision to Take the Influenza Vaccination in Japan

In this chapter, we investigate what people in Japan consider when deciding to take the influenza vaccination. We develop an economic model to explain the mechanism by which people decide to take the influenza vaccination. Using our model and the data obtained from a large-scale survey we conducted in Japan, we demonstrated that people make rational decisions about vaccinations after considering its cost and benefits. People consider the probability of infection, severity of the disease, and the vaccination’s effectiveness and side effects. The time discount rate is another consideration because the timing of costs and benefits of the vaccination differ. Risk aversion (fearing the contraction of the flu and vaccination’s side effects) also affects the decision. People also deviate from rationality—altruism and status quo bias play important roles in the decision-making. Overconfidence indirectly affects the decision via perception variables such as the subjective probability of infection and assessment of influenza’s severity. The decision also depends on attributes such as gender, age, and marital status. If the general perception of flu and vaccination is inaccurate, supplying accurate information regarding those may increase or decrease the vaccination rate, depending on whether this perception is, respectively, higher or lower than the objective rates. Thus, we examine whether the general perception is biased. Our survey suggests that disseminating information on the vaccination’s effectiveness may increase the rate of vaccination, whereas that on the probability of infection may have the opposite effect.