Population HIV Viremia and Epidemic Transition: Findings From Sequential Surveys in 6 Sub-Saharan African Countries

Testing and treatment targets may not fully capture the progress of the epidemic. Whether cascade gains translate into short-term reductions in new infections, as reflected by the incidence-to-prevalence ratio (IPR), remains uncertain.

We analyzed 2 rounds of Population-based HIV Impact Assessment surveys in Eswatini, Lesotho, Malawi, Tanzania, Uganda, and Zimbabwe (Round 1, 2015–2017; Round 2, 2019–2023) among adults aged 15–59 years. We estimated human immunodeficiency virus (HIV) prevalence, the 95–95–95 cascade, population viral load suppression (PVLS), population viremia (PV), HIV incidence, and IPR using survey-weighted methods. Population viremia was categorized as undiagnosed and viremic, diagnosed but not on antiretroviral therapy (ART), or on ART but not suppressed.

The sample included 113 970 Round 1 and 112 445 Round 2 participants. Across countries, PVLS ranged from 52.0% to 72.4% in Round 1 and from 74.5% to 88.0% in Round 2; PV ranged from 2.4% to 8.3% in Round 1 and from 1.0% to 4.7% in Round 2. In Round 2, undiagnosed infection accounted for most PV in 4 countries (53.1%–71.4%). Incidence estimates were lower in Round 2 in 5 countries, but CIs were wide and overlapping. The incidence-to-prevalence ratio ranged from 3.0% to 6.7% in Round 1 and from 2.1% to 5.1% in Round 2; estimates were <3% in Eswatini, Lesotho, and Malawi, but CIs included 3%.

Population viral load suppression increased, and PV declined in all countries, but precision for short-term IPR change was limited. Residual viremia was concentrated among undiagnosed adults, supporting targeted testing, rapid linkage, and treatment continuity.