While it reduces the probability of facing a primary (or vaccine-preventable) disease, vaccination may also introduce the risk of facing vaccine induced side effects. In this paper, we address the link between this feature of vaccination and attitudes toward risk. Risk aversion is shown to increase the propensity to vaccinate when the primary disease is lethal or when the risks of primary disease and of side effects are faced in different periods. When the primary disease is non-lethal and may occur together with side effects, we show how the effect of risk aversion is affected by the probability and severity of each disease. The implications of the introduction of random effects of primary disease and of random side effects are also analyzed.