The grey line plots the relationship between the per cell rate that CD4 T cells traffic out of drug sanctuaries (κτ0 day-1) and the effectiveness of antiretroviral therapy in the drug sanctuaries (z0), under the assumption that the drug sanctuaries are also immune sanctuaries (δ0 = 0.5 day-1,δ1 = 1 day-1). Boosting immune control in the sanctuaries so that there are equal infected cell clearance rates in each compartment (δ0 = δ1 = 1 day-1) acts additively with boosting cell trafficking rates so that the threshold for sustainable replication is decreased (black line). This figure reveals that antiretroviral therapy, trafficking therapy and immune therapy could all work in synergy to halt ongoing replication in drug sanctuaries. Guided by clinical findings, these plots assume that antiretroviral therapy is very effective in the main compartment (z1 = 0.97) and drug sanctuaries are very small in size compared to the main compartment.