REVIEW The contribution of unsafe blood transfusion to human immunodeficiency virus incidence in sub-Saharan Africa: reexamination of the 5% to 10% convention Malika M. Morar, 1 John P. Pitman, 2 Willi McFarland, 1 and Evan M. Bloch 3 BACKGROUND: Historical estimates have attributed 5% to 10% of new human immunodeficiency virus (HIV) infections in sub-Saharan Africa (SSA) to unsafe blood transfusions. Although frequently cited, the validity of this statistic is uncertain or outdated. Recent estimates suggest blood transfusion’s contribution to new HIV infections in the region may be much lower. STUDY DESIGN AND METHODS: We searched the peer-reviewed and gray literature for quantitative estimates of the specific contribution of unsafe blood transfusion to the proportion of new HIV infections occurring in SSA. The sources and methods used to generate attribution estimates were evaluated against published country-specific HIV prevalence data. RESULTS: Despite multiple secondary citations, a primary published source attributing 5% to 10% of new HIV infections to blood transfusions in SSA could not be established for the current era. The United Nations Programme on HIV and AIDS (UNAIDS) modes of transmission (MOT) reports representing 15 countries suggest that between 0 and 1.1% of new HIV infections per year (median, 0.2% or approx. two out of 1000 new infections each year) may be attributable to blood transfusions. CONCLUSION: Recent modeled estimates suggest that blood transfusions account for a very low proportion of new HIV infections in SSA, likely an order of magnitude lower than 5% to 10%. Direct quantification of risk is challenging given the paucity of data on the variables that impact transfusion-associated HIV. Specifically, data on HIV incidence in blood donors, blood bank laboratory test performance, and posttransfusion surveillance are lacking. Findings suggest an urgent need for improved surveillance and modeling of transfusion-associated HIV transmission in the region. T he global burden of human immunodeficiency virus (HIV) is disproportionately focused in sub- Saharan Africa (SSA). In 2014, an estimated 25.8 million people were living with HIV in SSA, and 1.4 million Africans were newly infected annually. 1 Sexual transmission is by far the predominant mode of transmis- sion in SSA, with lesser contributions from transactional sex, men who have sex with men, and injecting drug use. 2 While blood transfusion is thought to contribute the smallest proportion of new HIV infections in SSA, it remains the most efficient mode of transmission. 3 Trans- fusion of a single HIV-infected blood unit results in sero- conversion in the majority (89%-96%) of recipients. 4,5 More than four million units are collected and transfused each year in SSA, 6 yet transfusion-associated HIV infec- tions are rarely reported. Unsafe blood remains a bio- logically plausible mode of transmission, especially in countries with high background HIV incidence, deficient ABBREVIATIONS: MOT 5 modes of transmission; SSA 5 sub-Saharan Africa; TTI(s) 5 transfusion-transmitted infection(s); UNAIDS 5 United Nations Programme on HIV and AIDS; VNRBD(s) 5 voluntary, nonremunerated blood donation. From the 1 University of California at San Francisco, San Francisco, California; the 2 Institute of Science in Healthy Aging & health caRE (SHARE), University of Groningen, University Medical Center Groningen (UMCG), Groningen, The Netherlands; and the 3 Johns Hopkins University School of Medicine, Baltimore, Maryland. Address reprint requests to: Evan M. Bloch, MD, MS, Johns Hopkins University School of Medicine, 600 N. Wolfe Street/ Carnegie 446 D1, Baltimore, MD 21287-6667; e-mail: ebloch2@ jhmi.edu. Received for publication April 29, 2016; revision received June 21, 2016; and accepted July 28, 2016. doi:10.1111/trf.13816 V C 2016 AABB TRANSFUSION 2016;56;3121–3132 Volume 56, December 2016 TRANSFUSION 3121