Grant: O.G: STBBI Res.: Beyond HIV/AIDS/Hep. C- STBBI other than HIV/hep. C (general)

Herpes simplex virus types 1 and 2 (HSV-1 and 2) are common, sexually transmitted, incurable viral infections that cause oral ("cold sores") and anogenital herpes. HSV infections have considerable physical and psychological impacts, and can even cause death. HSV infections can also be asymptomatic, yet they cause a two- to three-fold increased risk of acquiring HIV infection, and can exacerbate disease in people living with HIV. Despite a robust vaccine pipeline, no effective biomedical measures exist for preventing HSV. Safe, effective medications for HSV treatment such as valacyclovir have existed for years. In the modern era of expanding pre- and post-exposure prophylaxis (PrEP and PEP) for preventing HIV and bacterial sexually transmitted infections, a key question is whether such strategies could work preventing HSV, and HSV-2 in particular, since this type causes more severe disease. Yet no clinical data exist. To plan for a full-scale randomized trial to address these questions in the future, we will conduct a pilot trial evaluating the feasibility and acceptability of valacyclovir as HSV-2 PEP and PrEP in gay, bisexual and other men who have sex with men (GBM) and transgender women in Canada. The most important feasibility question is whether participants consider these interventions acceptable, since this is a pre-requisite for any health interventions to have real-world impact. Other needed data include how common HSV-1 and 2 are in the intended population (prevalence), the rate at which people become infected (incidence), whether people take pills as intended (adherence), and an initial estimate of how well PrEP/PEP work (effect size). We will address these questions in a three-arm, open-label pilot trial at two experienced clinical trial sites in Toronto and Vancouver, and through close engagement with GBM community leaders. Our work will gather the first human data on this innovative approach to preventing a major viral STI.