Evidence from two rounds of Population HIV Impact Assessments of progress towards HIV epidemic control in adolescents aged 15–19 years in Eswatini, Lesotho, Malawi, and Zimbabwe: a cross-sectional study

There are more than 1 million adolescents aged 15–19 years living with HIV globally. Using two rounds of the Population HIV Impact Assessments (PHIAs), we describe incidence, prevalence, and UNAIDS 95–95–95 testing, treatment, and viral load suppression (VLS) indicators for adolescents living with HIV in four countries in southern Africa over time.

In this multinational cross-sectional study, we analysed data from two PHIA rounds in Eswatini (2016–17 and 2021), Lesotho (2016–17 and 2020), Malawi (2015–16 and 2020–21), and Zimbabwe (2015–16 and 2020). PHIAs are surveys distributed to randomly selected households, and participants were eligible if they had slept in the house the night before, were legally competent, and gave consent. Adolescents aged 15–19 years received rapid antibody HIV testing and provided blood samples. HIV incidence was estimated with avidity assays. Adolescents living with HIV were considered to be on antiretroviral therapy (ART) if they had detectable antiretrovirals in their blood or reported taking ART. VLS was defined as viral load of less than 1000 copies per mL. Survey-weighted proportions of adolescents living with HIV with known HIV status, on ART (among those with known HIV status), and VLS (among those on ART) were compared across survey rounds using Rao–Scott χ² tests adjusted for study weights with jackknife variance.

A total of 11 343 adolescents participated in round 1 (5947 [52·4%] were female and 5396 [47·6%] were male; 402 were living with HIV) and 10 849 in round 2 (5754 [53·0%] were female and 5095 [47·0%] were male; 318 were living with HIV). The estimated HIV incidence in round 1 was 1·05% (95% CI 0·27–1·83) in Eswatini, 0·37% (0·00–0·81) in Lesotho, 0·12% (0·00–0·32) in Malawi, and 0·17% (0·00–0·38) in Zimbabwe. The estimated HIV incidence in round 2 was unavailable in Eswatini due to the small sample size, 0·38% (0·00–0·82) in Lesotho, 0·20% (0·00–0·43) in Malawi, and 0·42% (0·03–0·81) in Zimbabwe. The round 2 PHIA surveys in Lesotho, Malawi, and Zimbabwe showed that approximately 12 000 new HIV infections occurred annually in adolescents aged 15–19 years. Across all four countries, there was an increase between round 1 and round 2 in HIV status knowledge (63·8% to 81·2%, p<0·0001) and in ART coverage (90·1% to 96·3%, p=0·041), whereas there was no significant change in VLS (79·3% to 85·4%, p=0·15).

Despite improvements in HIV status knowledge and ART coverage among adolescents aged 15–19 years living with HIV in four countries, the estimated HIV incidence did not decline and only 81% of adolescents living with HIV knew their status in 2020–21. Increasing testing in this age group is urgently needed to accelerate progress towards epidemic control.