Speaker
Description
The HIV/AIDS epidemic remains a major global health challenge, with no definitive cure currently available. Following the World Health Organization’s 2014 recommendations, a preventive treatment known as Pre-Exposure Prophylaxis (PrEP) has been adopted worldwide, introduced in France in 2016, to curb HIV transmission. We propose here a new compartmental epidemiological model that explicitly accounts for the limited duration of PrEP’s protective effect. The PrEP compartment is described by an age-structured hyperbolic equation, while initiation of PrEP use is governed by a differential equation. Together, these lead to a nonlinear differential–difference system with discrete delays. We analyze both local stability and global dynamics of the system. Using numerical simulations informed by data from the French population of men who have sex with men (MSM), we validate the accuracy of our model. In particular, we show that combining logistic time dynamics with a Hill-type function yields an excellent fit to the available data. The model is further extended by incorporating a variable force of infection among PrEP users, influenced not only by the size of the infected population but also by political and economic factors. This reflects the reality that socioeconomic constraints can restrict access to PrEP for part of the population. Finally, we investigate epidemic dynamics under a non-monotonic recruitment rate. Altogether, these results provide new insights into the potential trajectory of the HIV epidemic in France, under the assumption of sustained PrEP uptake within the population.
