Vaccines against Emerging Sexually Transmitted Infections: Current Preventive Tools and Future Perspectives

Vaccines have historically played a pivotal role in reducing the burden of infectious diseases andnow play a crucial role in the setting of sexually transmitted infections (STIs). However, there remainseveral unmet goals: vaccines are available only for viral STIs, vaccination accessibility anduptake remain disproportionate worldwide, and no effective vaccine has been developed for HCV.Moreover, there are no vaccines against bacterial STIs: fewer investments in research have beenmade, because vaccines are not a top priority due to the availability of effective treatments. However,higher rates of resistance to all available antibiotics has led to a shift in research priorities. Severalpromising vaccine candidates have been identified or are being investigated in pre-clinical or clinicaltrials, although further understanding of the immunogenicity, effectiveness and delivery strategiesof already licensed vaccines is needed. This paper focuses on current research efforts to developvaccines against bacterial (e.g. gonorrhoea, chlamydia and syphilis) and viral (e.g. HCV) STIs. Wealso review current indications and evidence of effectiveness of already available vaccines (e.g. HAV,HBV and HPV) and discuss open issues.