Declining HIV incidence in sub-Saharan Africa: a systematic review and meta-analysis of empiric data

Background: UNAIDS models suggest HIV incidence is declining in sub-Saharan Africa; however, it is unclear whether modeled trends are supported by empirical evidence. Methods: We conducted a systematic review and meta-analysis of adult HIV incidence data from sub-Saharan Africa by searching Embase, Scopus, PubMed, and OVID databases and technical reports published between January 1, 2010 and July 23, 2019. We included studies that directly measured incidence from blood samples. Incidence data were abstracted according to population risk group, geographic location, sex, intervention arm, and calendar period. Weighted regression models were used to assess incidence trends across general population studies by sex. We also identified studies reporting ≥3 incidence measurements since 2010 and assessed trends within them. Findings: 292 studies met inclusion criteria. Most studies were conducted in South Africa (n=102), Uganda (n=46), and Kenya (n=41); there were 27 countries with no published incidence data, most in western and central Africa. Across general population studies, average annual incidence declines since 2010 were 0.16/1000 person-years (95%CI:0.06-0.26;p=0.004) among men and 0.16/1000 person-years (95%CI: -0.01-0.33;p=0.060) among women in eastern Africa, and 0.25/1000 person-years (95%CI:0.17-034;p<0.0001) among men and 0.42/1000 person-years (95%CI:0.23-0.62;p=0.0002) among women in southern Africa. In 9/10 studies with multiple measurements, incidence declined over time. Incidence was typically higher in women than men (median ratio=1.45, IQR: 1.12-1.83) with increasing sex disparity over time. Interpretation: Empirical incidence data show the rate of new HIV infections is declining in eastern and southern Africa. However, recent incidence data are non-existent or very limited for many countries, particularly in western and central Africa.