Blaser N., Wettstein C., Estill J., Vizcaya L.S., Wandeler G., Egger M., Keiser O.
Institute of Social and Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012 Bern, Switzerland; Department of Infectious Diseases, University Hospital Bern, Switzerland; Department of Infectious Diseases, University of Dakar, Dakar, Senegal; School of Public Health and Family Medicine, University of Cape Town, South Africa
Blaser, N., Institute of Social and Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012 Bern, Switzerland; Wettstein, C., Institute of Social and Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012 Bern, Switzerland; Estill, J., Institute of Social and Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012 Bern, Switzerland; Vizcaya, L.S., Institute of Social and Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012 Bern, Switzerland; Wandeler, G., Institute of Social and Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012 Bern, Switzerland, Department of Infectious Diseases, University Hospital Bern, Switzerland, Department of Infectious Diseases, University of Dakar, Dakar, Senegal; Egger, M., Institute of Social and Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012 Bern, Switzerland, School of Public Health and Family Medicine, University of Cape Town, South Africa; Keiser, O., Institute of Social and Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012 Bern, Switzerland
OBJECTIVES:: HIV 'treatment as prevention' (TasP) describes early treatment of HIV-infected patients intended to reduce viral load and transmission. Crucial assumptions for estimating TasPÊ1/4s effectiveness are the underlying estimates of transmission risk. We aimed to determine transmission risk during primary infection, and describe the relation of HIV transmission risk to viral load. DESIGN:: A systematic review and meta-analysis. METHODS:: We searched PubMed and Embase databases for studies that established a relationship between viral load and transmission risk, or primary infection and transmission risk, in serodiscordant couples. We analysed assumptions about the relationship between viral load and transmission risk, and between duration of primary infection and transmission risk. RESULTS:: We found 36 eligible articles, based on six different study populations. Studies consistently found that higher viral loads lead to higher HIV transmission rates, but assumptions about the shape of this increase varied from exponential increase to saturation. The assumed duration of primary infection ranged from 1.5 to 12 months; for each additional month, the log10 transmission rate ratio between primary and asymptomatic infection decreased by 0.40. CONCLUSION:: Assumptions and estimates of the relationship between viral load and transmission risk, and the relationship between primary infection and transmission risk, vary substantially and predictions of TasPÊ1/4s effectiveness should take this uncertainty into account. © 2014 Wolters Kluwer Health.