In the presence of immune therapy directed at the drug sanctuaries, the cell clearance rate in the drug sanctuaries can be increased. In both compartments, susceptible cells are cleared at a per cell rate of α day-1. The resulting set of coupled, non-linear ordinary differential equations describing the change in the number of susceptible cells (Eqs 1 and 2) and infected cells (Eqs 3 and 4) in the drug sanctuaries and main compartment over time is provided below.