Previous studies have found that the use of HIV pre-exposure prophylaxis (HIV PrEP) reduces HIV transmission. However, there is a concern about a potential association between implementing HIV PrEP and the growing incidence rates of sexually transmitted infections (STIs) in the US. The authors conducted a quasi-experimental (interrupted time series) analysis of STIs (syphilis, gonorrhoea and chlamydia) rates before (2000–2012) and after (2013–2017) the implementation of HIV PrEP. HIV PrEP utilisation was defined as the number of people taking tenofovir disoproxil fumarate/emtricitabine for HIV prevention. They found that HIV PrEP implementation was associated with 25% (relative risk [RR] 1.254, 95%CI 1.245-1.263) and 26% (RR 1.260, 95%CI 1.257-1.264) increases in syphilis and gonorrhoea rates, respectively; and a 12% reduction in chlamydia rates (RR 0.884, 95%CI 0.883-0.885). HIV PrEP utilisation correlated with the number of cases of syphilis, gonorrhoea and chlamydia. At the state level, HIV PrEP also correlated with the number of cases of syphilis, gonorrhoea and chlamydia. Therefore the implementation and utilisation of HIV PrEP in the US is associated with increased rates of STIs.
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