Modeling the impact of imperfect HIV vaccines on the incidence of the infection

One concern about HIV vaccine trials is that participants might develop a false sense of security and increase their risk behavior. This fear has (at least partially) impaired the development of extensive clinical trials on HIV vaccines and is, in principle, justified. In this paper, we develop a dynamical model which allows experiments on the effects of an imperfect vaccine on a population prone to change its risk behavior. Our results show that even the poorest of the candidate vaccines to be seriously considered may have beneficial effects on reducing transmission, even when risk behaviors increases.