Several barriers limit the development of
vaccines against
sexually transmitted diseases (
STIs). Critical scientific information is missing that makes the feasibility and the likelihood of success of
vaccines against
genital herpes, chlamydia,
gonorrhea and trichomonas uncertain: the immunity induced by natural
infection is absent or imperfect which seriously limits the capacity to define the types of immune responses that an effective
vaccine must induce. Reliable animal models are lacking and a number of crucial clinical questions are still unanswered about the goal of these
vaccines and definition of endpoints for clinical trials. In the absence of a clear recognition of the need for
vaccines against these diseases, there is no motivation for public or private research and industry to invest in the development of
vaccines against
STIs. The
STI burden should be evaluated not only in terms of mortality and morbidity, but also in terms of economic and psycho-social impact. A global public-private consortium could mobilize the joint efforts of all stakeholders involved in the research, development and implementation of
STI vaccines of the public and private sectors; ensure that sufficient resources are applied to R&D of
vaccines against these
STIs; and provide the pull-push forces that are necessary to overcome the barriers to develop safe and effective
vaccines against these diseases.