Community Viral Load as a Measure for Assessment of HIV Treatment as Prevention

April 2013 - Combination Prevention

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Miller, W.C., Powers, K.A., Smith, M.K., et al. The Lancet Infectious Diseases (March 2013).

The authors presented the limitations of using community viral load as a measure for assessing HIV epidemics, saying that the strategy has two potential uses: as a routine measure of a community's uptake of antiretroviral therapy, and as an indicator of HIV transmission within a community. The authors recommended caution in interpreting aggregate measures of viral load. The measurement is centered on individuals linked to and retained in HIV care, which creates a biased estimate by excluding undiagnosed individuals or those who are HIV-positive, yet not in care. Most communities do not have sufficient numbers of individuals retained in care to provide accurate estimates. Further, viral load varies over time; thus, the timing of measurement could affect accuracy. Accounting for a population's HIV-infected and uninfected people is important for understanding HIV transmission; current measures do not address HIV prevalence effects. Moreover, viral load distributions are often multimodal, which complicates aggregate measures. Community viral load is an inadequate measure of the potential for ongoing HIV transmission, because it represents a combination of sexual behaviors, networks, and viral loads among HIV-positive individuals, and does not identify individual transmission routes. According to the authors, a combination of measures monitoring the different aspects of the care cascade--including HIV testing, diagnosis, engagement in care, retention in care, and viral suppression--will be critical to an accurate understanding of an HIV epidemic.

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