However, we observe no relationship between the parameter determining the increased infectiousness during early infection and the long-term impact on HIV incidence of treatment interventions. The extent to which individuals in early infection are more infectious is highly uncertain. However, early transmission may be an important determinant in the outcome of short-term trials and evaluation of programs. The fraction of early transmission depends on biological factors, behavioral patterns, and epidemic stage and alone does not predict long-term intervention impacts. This was because more early transmission resulted in a shorter generation time, in which case lower values for the basic reproductive number (R 0) are consistent with observed epidemic growth, and R 0 was negatively correlated with long-term intervention impact. However, the proportion of early transmission was not strongly related to the long-term reduction in incidence.
Immediately after ART was introduced, more early transmission was associated with a smaller reduction in HIV incidence rate-consistent with the concern that a large amount of early transmission reduces the impact of treatment on incidence. The model was calibrated to HIV prevalence data from South Africa using a Bayesian framework. The model includes stages of HIV infection, flexible sexual mixing, and changes in risk behavior over the epidemic. We created a mathematical model of a heterosexual HIV epidemic to investigate how the proportion of early transmission affects the impact of ART on reducing HIV incidence. Thus, a large proportion of HIV transmission during a period of high infectiousness in the first few months after infection (“early transmission”) is perceived as a threat to the impact of HIV “treatment-as-prevention” strategies.
Antiretroviral therapy (ART) reduces the infectiousness of HIV-infected persons, but only after testing, linkage to care, and successful viral suppression.