“…We feel this case is fundamentally more appropriate in the developed world than the alternative hypothesis that demand is driven by the disease incidence, especially for those common vaccine preventable infections which currently have very low or even zero incidence. To this aim we study the dynamics of vaccine uptake for a homogeneously mixing vaccine preventable SIR disease [6] with vital dynamics and vaccination by a perfect vaccine under the following circumstances: a) vaccination is voluntary; b) the vaccine has a constant probability to generate severe, non-lethal, side effects; c) the perceived risk of suffering serious disease following infection is steadily low, so that the vaccine demand is essentially related, through a decreasing function, to the perceived risk M of suffering a vaccine associated side effect; d) the perceived risk M is evaluated from publicly available information on current, past, or even future (through expectations) trends of side effects caused, or attributed, to the vaccine. In particular, in order to evaluate the risk of VSE, parents are assumed to use the public information on the current, or past, reported incidence of VSE, or the prevalence of those who suffered side effects.…”