Economic and behavioral factors in an individual's decision to take the influenza vaccination in Japan

In this paper, 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.

► We identify determinants of the willingness to be vaccinated against flu in Japan. ► We construct an economic model in which people rationally decide to be vaccinated. ► The probability and severity of disease and effectiveness of vaccine are important. ► Time discount rate, risk aversion, altruism, and status quo bias are also important. ► While information on vaccine will raise vaccination rate, that on illness will not.