Innovations in the biomedical prevention, diagnosis, and service delivery of HIV and other sexually transmitted infections

Abstract

The interconnectedness of the global HIV and sexually transmitted infection (STI) epidemics necessitates integrated strategies to address both. This Series paper highlights the biological link between HIV and STIs, and describes the successful progress in HIV response versus STI response over the past decades. The concept of undetectable=untransmissible (U=U) in HIV treatment has revolutionised HIV prevention by reducing stigma and promoting early treatment. In line with this approach, we discuss the role of chronic suppressive therapy for herpes simplex virus type 2 and the importance of the accurate diagnosis and treatment of curable STIs to prevent transmission between sexual partners. This Series paper explores the potential of pre-exposure prophylaxis (PrEP) for HIV in different forms (eg, daily oral PrEP, event-driven PrEP, and long-acting injectable PrEP), and highlights the challenges of adherence to daily regimens and the promise of longer-acting agents, such as cabotegravir and lenacapavir. The potential of doxycycline post-exposure prophylaxis for the prevention of bacterial STIs is also discussed, with concerns about antimicrobial resistance. Although vaccine development for HIV and STIs is a key biomedical advance, we discuss the challenges and possibilities of developing effective vaccines, including lessons learnt from previous HIV vaccine trials, the potential of mRNA-based vaccines for herpes simplex virus, ongoing trials for gonorrhoea and chlamydia vaccines, and the impact of existing human papillomavirus and mpox vaccines. Diagnostic innovations emphasise the importance of point-of-care tests for HIV and STIs. This Series paper discusses the benefits, landscape, and pipeline of rapid diagnostic tests (eg, lateral flow tests and molecular assays) and the challenges of implementing these tests in low-resource settings, particularly the need for rapid results to inform clinical decisions, promote convenience, and reduce cost. This Series paper also addresses innovations in service delivery and advocates for integrated and person-centred approaches (eg, differentiated services) that combine HIV and STI services, and highlights the potential of community-based and home-based models to improve access and reduce stigma.