Improving adherence to a daily PrEP regimen is key when considering long-time partnerships

Area of Science:

• Epidemiology
• Mathematical Biology
• Public Health

Background:

• HIV prevention strategies are evolving with the introduction of pre-exposure prophylaxis (PrEP).
• Understanding transmission dynamics across different partnership structures (casual, monogamous, non-monogamous) is crucial for effective HIV control.
• PrEP uptake and adherence vary, influenced by risk perception and prescription access.

Purpose of the Study:

• To develop a population model of HIV transmission incorporating PrEP use across diverse partnership types.
• To analyze the impact of PrEP initiation, suspension, and adherence on HIV reproduction numbers and elasticity.
• To identify key factors influencing HIV incidence in populations with varying PrEP adherence levels.

Main Methods:

• Development of a compartmental population model for HIV transmission.
• Inclusion of susceptible individuals (on PrEP and not on PrEP) and infected individuals.
• Application of Markov chain theory to model transitions between susceptible states, particularly for non-monogamous partnerships with differential susceptibility.

Main Results:

• The model demonstrates that PrEP adherence significantly impacts the reproduction number and elasticity indices.
• Multi-parameter analysis indicates that increased PrEP adherence has the most substantial effect in reducing new HIV infections.
• Differential susceptibility within non-monogamous partnerships presents complex transmission dynamics.

Conclusions:

• Optimizing PrEP adherence is a critical intervention for reducing HIV transmission across various sexual partnership structures.
• Mathematical modeling, including Markov chains, is valuable for understanding complex HIV epidemiology with interventions like PrEP.
• Public health strategies should focus on enhancing PrEP adherence to maximize its impact on HIV prevention efforts.