The central theme of this first SACEMA Quarterly Epidemiological Update of 2010 is the rate of occurrence of new HIV infections – also known as HIV incidence. The issue is examined through three distinct perspectives: 1) Recent advances in measuring the HIV incidence in a population, and/or how it changes over time, 2) estimating the relative importance of various ‘modes of transmission’ in contributing to new cases of HIV infection, and 3) the use of antiretroviral treatment of infected individuals to curb their infectivity and hence reduce HIV incidence.
Modes of transmission
Effective planning and delivery of HIV prevention programs depends on an understanding of where new infections are occurring and on the behaviours associated with those infections. A simple mathematical model developed by the UNAIDS Reference Group for Estimates, Modelling and Projections helps countries estimate the proportion of new infections that occur through key transmission modes. This type of in-country analysis could be used to inform the planning of appropriately targeted intervention programmes. However, improved biological and behavioural surveillance in countries is needed to provide more reliable data for input into such analyses.