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S03.1 Impact of HIV PrEP on risk compensation and STI epidemiology – what does the evidence show?
  1. Helen Ward
  1. Imperial College London, London, UK


Introduction From the earliest days of the HIV epidemic there has been a close relationship with other sexually transmitted infections (STI). The shared transmission routes and determinants were reflected in high levels of synergy in the epidemics. Early preventive interventions for HIV – including changes in partner numbers and selection, use of barriers and changes in sexual practices towards safer sex – were ‘infection agnostic’, and had a dramatic impact on bacterial STI, with levels of syphilis and gonorrhoea falling to historic lows in some high-income settings. In contrast, many newer technologies for HIV prevention are ‘infection specific’, leading to the potential for divergent epidemics of HIV and other STI

Method and results We review evidence to date of the impact of PrEP on (a) risk compensation, and (b) STI rates in a range of populations and settings. We synthesize data from earlier systematic reviews, and review the association between PrEP use and bacterial STIs in cis-gender women. Detailed results will be presented; briefly, early randomised control trials reported no increase in STIs or changes in sexual practices; more recent studies in less controlled environments such as open-label or demonstration projects have often reported increased STI incidence and risk compensation.The majority of evidence is from studies in men who have sex with men and transgender women

Discussion An increase in condomless sex is not an unintended consequence of PrEP. For decades HIV prevention was limited because many people prefer sex without condoms. Now we have the technology to do this without the fear of HIV, just as the oral contraceptive pill (OCP) removed the fear of pregnancy for many women. While that may contribute to an increase in STI, as the OCP did, we should use this as an opportunity to argue for renewed investment in STI control programmes and research.

Disclosure No significant relationships.

  • PrEP
  • prevention
  • epidemiology
  • systematic review

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