However, if 100% prevention of infection is not possible to achieve,

then some consideration needs to be given to a vaccine that mainly prevents ascending infections that lead to disease pathology. In fact, one argument might be to focus on the disease pathology, as this is the major consequence of infection. A vaccine that could do both would clearly be ideal. The reality though is that any vaccine needs to be evaluated learn more in clinical trials and the measurement of reduction of infection is more readily quantifiable than immune-mediated damage, such as PID or infertility. Until recently, the majority of efforts have focused on evaluating prototype vaccines by measuring the reduction in infectious burden following live challenge of vaccinated animals, almost totally in the mouse model. As already mentioned, these vaccines are much easier to evaluate through the regulatory process. Recently though, there have been increasing and encouraging reports of vaccine strategies that can protect against the downstream adverse pathology [95]. The other aspect of a C. trachomatis vaccine is the target group. All efforts to date have been directed at developing prophylactic vaccines, with the assumption that the vaccine would be administered to young girls prior to sexual activity. In reality though, a therapeutic vaccine that could be safely administered

to women who either had a past or even current infection, would be very useful. There are very few published studies in this area, although the report of Carey et al. [86] in the C. muridarum – mouse model Ketanserin BAY 73-4506 order suggest that vaccinating either presently infected or previously infected individuals may not result in a strong immune response. There are no absolute criteria for the properties that a vaccine should have before it can be recommended for wide use in programmes to improve the health of populations. The World Health Organization recommends vaccines which have long-term protection and high efficacy [89] and [96], however, vaccines which offer lower levels

of protection are suggested for use in certain circumstances or populations [97], [98], [99], [100] and [101]. When it is anticipated that only partially effective vaccines may become available, mathematical models have been used to investigate the potential epidemiological impact for the infectious disease in question, associated with different vaccine properties and implementation strategies [102]. Most theoretical vaccine modelling studies for sexually transmissible infections have been for HIV (e.g. [103], [104], [105], [106], [107], [108], [109] and [110]), but numerous vaccine modelling studies have emerged for HPV in recent years due to the availability and implementation of the cervical cancer vaccine in many countries [111], [112], [113] and [114].