BACKGROUND: Associations have been observed between an aggregate viral load measure, the community viral load (CVL) and new HIV diagnoses. The CVL aggregates viral loads within chosen geographic areas, restricting inferences about HIV acquisition risk to these areas. We develop a more precise metric, the Network Viral Load (NVL) to measure the composite viral load within a risk network of an HIV negative individual.
METHODS: We examined the relationship between NVL and HIV infection among Young Men who have Sex with Men (YMSM) in Chicago, United States. Networks were generated using Respondent Driven Sampling. NVL was defined as the prevalence of viremic individuals in one’s risk network, characterized as those with a viral load >20k copies/mL. Permutation tests were conducted to account for dependency.
RESULTS: After controlling for total connections, age, substance use during sex, syphilis diagnosis (previous 12 months), and frequency of condomless anal sex (previous 6 months), we found a positive association between NVL and HIV infection. Compared to a network with all HIV-seronegative members, the odds of HIV infection with a NVL of <10% viremia were 1.85 (95% C.I. 1.18-2.92) times higher and a NVL of >10% viremia were 2.73 (95% C.I. 1.54-4.85) times higher.
CONCLUSION: We found a positive association between NVL and HIV seroprevalence. While limited in its ability to infer causality, NVL could have substantial public health implications for persons most at risk for HIV infection given that this novel metric avoids overreliance on individual level behavior or broad community indices.
Network viral load: A critical metric for HIV elimination
Journal of Acquired Immune Deficiency Syndromes, 77 (2), 167-174. doi: 10.1097/QAI.0000000000001584. PMCID: PMC5762423.