Potential testing and treatment strategies for eliminating HIV

Theoretically, HIV could be eliminated from endemic countries if entire populations were tested and enough infected individuals were treated with antiretroviral drugs, but the frequency of testing required and the proportion of those infected who would need to receive treatment are unclear. Mirjam Kretzschmar et al. (pp. 15538– 15543) developed a model of HIV transmission that incorporates the concept of an elimination threshold, defined as the level of treatment above which the infection cannot persist in an endemic steady state. Similar to previous models, the authors’ model describes the progression of infection through various stages and uses estimates of the speed of transmission between individuals and the rate of treatment uptake and dropout to predict the likely spread of infection. The authors also considered variations in transmission dynamics over the course of infection, as an estimated 36% of transmissions occur during the first year of infection, and many of these would not be prevented by annual screening. According to the authors, annual screening combined with antiretroviral drug therapy for all HIVinfected individuals must achieve more than 85% coverage in order to approach elimination in sub-Saharan African countries. However, additional interventions that substantially reduce the reproduction rate of the virus (for example, by lowering the partner change rate in high-risk subgroups) can reduce the elimination threshold to a more feasible number. — C.B.