Fig. 1

Structure of the dynamic model of HIV-1 transmission, ART rollout and resistance emergence (upper panel), and model outputs with colours corresponding to Figs. 2 and 3 (lower panel). The population is split into six compartments: susceptible to HIV-1 (\(S\)); infected with a drug-sensitive strain and either untreated (\(I\)) or treated with first-line ART (\(T\)); infected with a drug-resistant strain and either untreated (\(J\)), treated with first-line ART (\(U\)) or treated with second-line ART (\(V\)). The model has ten parameters: transmission rate \(\beta\); maximal treatment rate \(\tau\) scaled by a sigmoid function \(f\left(t,\nu ,\xi \right)\) (controlled by two parameters for shift \(\nu\) and slope \(\xi\)); rate at which de novo NNRTI resistance emerges during treatment (\(\omega\)); rate of switching to second-line ART (\(\kappa\)); rate of AIDS-related mortality (\(\delta\)); rate of background mortality (\(\mu\)); rate of population growth (\(\eta\)); and the initial proportion of NNRTI resistance \(\iota\) (not shown)