Objective: HIV Testing and Counselling (TC) programmes are being scaled-up as part of efforts to provide universal access to antiretroviral treatment (ART).
Methods and findings: Mathematical modelling of TC in Zimbabwe shows that if universal access is to be sustained, TC must include prevention counselling that enables behaviour change among infected and uninfected individuals. The predicted impact TC is modest, but improved programmes could generate substantial reductions in incidence, reducing need for ART in the long-term.
Conclusions: TC programmes that focus only on identifying those in need of treatment will not be sufficient to bring the epidemic under control.