HIV pre-exposure prophylaxis and sexually transmitted infections: intersection and opportunity

Abstract

Pre-exposure prophylaxis (PrEP) has revolutionized HIV prevention, but PrEP does not protect against other sexually transmitted infections (STIs). Rates of STIs are rising worldwide, with notably high incidences among PrEP-using men who have sex with men in high-income countries; in low-income and middle-income countries, data are sparse, but results from a limited number of studies among African women initiating and taking PrEP have shown high STI prevalence and incidence. Efforts aimed at markedly reducing HIV in populations worldwide include a major focus on increasing PrEP use, along with improving HIV testing and treatment in order to eliminate HIV transmission. Together, these efforts could augment continued expansion of the global STI epidemic, but they could alternatively create an opportunity to improve STI control, including the development of comprehensive sexual health programmes and research to develop new STI prevention strategies. The introduction of PrEP globally has been characterized by challenges and many successes, and its role as part of a range of robust strategies to reduce HIV infections is clear. Looking ahead, understanding rising rates of curable STIs and their relationship to HIV prevention, and considering the future directions for synergies in PrEP and STI prevention will be integral to improving sexual health.

Figure 1.. HIV infection and PrEP mechanism of action.

a. After an unprotected exposure, HIV integrates into CD4 cells, replicates, and infects other CD4 cells. b. A single pre-exposure prophylaxis (PrEP) tablet, taken daily, stops HIV from replicating and, therefore, prevents acquisition of HIV in the event of an exposure. Current emtricitabine-tenofovir disoproxil fumarate (FTC/TDF) and FTC/tenofovir alafenamide (TAF) PrEP treatments work against reverse transcriptase enzymes but other, future PrEP agents could have antiretroviral activity against other HIV components.