PrEP-associated screening reduces N. gonorrhoeae transmission but increases case notifications among MSM: a modeling study

The rapid scale-up of HIV pre-exposure prophylaxis (PrEP) among men who have sex with men has coincided with rising rates of bacterial sexually transmitted infections (STIs), particularly Neisseria gonorrhoeae. This temporal association has raised concerns that PrEP may be driving a new STI epidemic. However, the epidemiological impact of PrEP reflects a trade-off between potential behavioral risk compensation, which increases transmission risk, and intensified clinical surveillance, which shortens infection duration. Determining whether PrEP amplifies or mitigates STI transmission therefore requires understanding how these competing effects balance at the population level. To address this question, we develop a transmission model stratified by sexual activity and PrEP use, derive simple analytical conditions governing changes in prevalence, incidence, and notification rates, and evaluate these dynamics using empirically informed parameter estimates. Our analysis demonstrates that current quarterly screening guidelines are generally sufficient to reduce both the true endemic prevalence and incidence of N. gonorrhoeae, successfully overcompensating for plausible reductions in condom use. We also confirm and expand on previous findings that clinical notification rates may surge even as the true disease burden declines, driven by the detection of previously undiagnosed asymptomatic infections. These findings suggest a shift in focus from the potential impact of PrEP on STI transmission to the consequences of increased STI diagnoses and treatment, particularly whether greater antibiotic consumption may accelerate the spread of antimicrobial resistance in N. gonorrhoeae.