Notice that the effective reproductive number is equal to the rate at which one infected cell infects others (βX^0(1−z0)/u0 day-1), multiplied by the mean residence time of infected cells in drug sanctuaries (1/(δ0 + κτ0) days). With this expression, it is clear that the effective reproductive number can be reduced by either: increasing the rate that cells traffic through drug sanctuaries (higher κ); reducing the number of susceptible cells (target cells) in drug sanctuaries (lower X^0); increasing the effectiveness of antiretroviral therapy in drug sanctuaries (higher z0); or boosting immune control and thus increasing the clearance rate of infected cells in drug sanctuaries (higher δ0).