The theoretical impact and cost-effectiveness of vaccines that protect against sexually transmitted infections and disease.

Sexually transmitted diseases, a source of widespread morbidity and sometimes mortality, are caused by a diverse group of infections with a common route of transmission. Existing vaccines against hepatitis B virus (HBV) and human papilloma virus 16, 18, 6 and 11 are highly efficacious and cost effective. In reviewing the potential role for other vaccines against sexually transmitted infections (STIs) a series of questions needs to be addressed about the burden of disease, the potential characteristics of a new vaccine, and the impact of other interventions. These questions can be viewed in the light of the population dynamics of sexually transmitted infections as a group and how a vaccine can impact these dynamics. Mathematical models show the potential for substantial impact, especially if vaccines are widely used. To better make the case for sexually transmitted infection vaccines we need better data and analyses of the burden of disease, especially severe disease. However, cost effectiveness analyses using a wide range of assumptions show that STI vaccines would be cost effective and their development a worthwhile investment.