Role of immunisation in preventing infectious diseases, including for STIs

Overview

Vaccination is an effective, increasingly important preventive strategy for a subset of STIs with an available vaccine - principally HPV (preventing genital warts and HPV-related cancers) and hepatitis B (sexually transmissible, vaccine-preventable) - though most bacterial STIs (chlamydia, gonorrhoea, syphilis) currently have no available vaccine
HPV vaccination programmes have achieved substantial population-level reductions in HPV-related disease (genital warts, cervical dysplasia) in settings with high vaccine uptake, representing one of the clearest public health successes in STI prevention

Vaccine-induced immunity before sexual debut prevents infection with vaccine-covered genotypes before any exposure occurs - this is the mechanistic basis for recommending HPV vaccination at a young age (before likely sexual activity begins), maximising the population of individuals vaccinated prior to any HPV exposure

Vaccination status/history should be reviewed as part of comprehensive sexual health assessment, with catch-up vaccination offered to eligible individuals who missed routine adolescent vaccination
Vaccination does not eliminate the need for other STI prevention measures (condom use, regular screening) given both incomplete genotype coverage (for HPV) and the absence of vaccines for most other STIs

HPV vaccination: current formulations cover multiple high- and low-risk genotypes; most effective when given before sexual debut but still offers benefit with catch-up vaccination in already sexually active individuals (protecting against genotypes not yet acquired)
Hepatitis B vaccination: part of routine immunisation schedules in most jurisdictions, with catch-up vaccination for non-immune individuals at ongoing risk

HPV vaccination and cervical/anal/oropharyngeal cancer prevention, hepatitis B vaccination and chronic infection prevention, absence of vaccines for chlamydia/gonorrhoea/syphilis/HIV (ongoing reliance on behavioural/testing-based prevention for these)

HPV vaccination still provides meaningful benefit even in individuals who are already sexually active, since it protects against genotypes not yet acquired - vaccination should not be withheld or considered "too late" simply because sexual debut has already occurred

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