Community viral load as a measure for assessment of HIV treatment as prevention

Community viral load (CVL), an aggregation of individual viral loads of HIV-infected persons within a defined community, has been proposed as a useful metric for monitoring HIV treatment uptake and quantifying its impact on transmission. The first publications regarding CVL appeared in 2009 and the metric was subsequently incorporated into the United States National HIV/AIDS Strategy. Although CVL is intuitively appealing, it has several theoretical limitations and biases that require further evaluation. These limitations and biases can be categorized in four areas related to: 1) selection and measurement issues in calculating CVL among HIV-infected persons, 2) the importance of HIV prevalence in determining the potential for ongoing HIV transmission, 3) interpretation of CVL and its impact on ongoing HIV transmission in a community, and 4) the ecological fallacy (ecological bias). These potential issues deserve careful assessment as CVL is being considered as a public health metric to assess the impact of HIV care on prevention