Table 1. Overview of successive addition of components and structures to each of the nine models.

Component	Model A	Sub-Model B1	Sub-Model B2	Model B	Sub-Model C1	Sub-Model C2	Sub-Model C3	Model C	Model D
Prevalence density functiona	X	X	X	X			X
Age-structured population		X		X	X	X	X	X	X
Transmission probability by disease stage			X	X	X	X	X	X	X
Heterogeneity in sexual behavior					X			X	X
STI co-factors, male circumcision, and condom use						X		X	X
Up-to-date ART effectiveness assumptions							X	X	X
Current ART scale-up from 2003 onwards									X

^aThis artificial prevalence density function was introduced by Granich et al. [9] to mimic processes that result in the observed leveling off of the HIV epidemic. In the more comprehensive models of our analysis we replaced this prevalence density function by the actual processes that may be responsible for the leveling off.