HIV incidence and prevalence among adults in Mozambique: estimates from the Population-based HIV Impact Assessment Survey (INSIDA 2021) and district-level modelling

Abstract

Introduction: Accurate information is needed to prioritize programmes and resources that address gaps in the HIV response. We examined findings from the 2021 Mozambique Population-based HIV Impact Assessment (INSIDA) survey, complemented with subnational model-based estimates of the number of new infections and district-level incidence to gauge progress in the HIV response and guide future priorities.

Methods: INSIDA 2021, a nationally representative cross-sectional household survey, measured national HIV incidence, national and provincial HIV prevalence, and factors associated with HIV. Consenting adults aged 15 years and older were interviewed and tested for HIV using the national diagnostic algorithm, followed by laboratory-based confirmation of HIV status. Testing for viral load, limiting antigen avidity and the presence of antiretrovirals were used to estimate HIV incidence. The Naomi model, a Bayesian small-area estimation model combining the INSIDA 2021 survey and routine HIV service delivery data, estimated provincial and district-level HIV incidence and district-level prevalence. Weighted HIV prevalence estimates, stratified by sex, are reported and factors associated with HIV infection modelled via multivariate logistic regression.

Results: National HIV prevalence was 12.5% (95% CI: 11.5-13.4) among adults 15 years and older, and national HIV incidence was 4.3 (95% CI: 2.3-6.3) per 1000 HIV-negative adults in 2021. Per model estimates, there were 84,000 (95% CI: 80,000-89,000) new infections per year, 55,000 among women (95% CI: 52,000-58,000) and 30,000 (95% CI: 28,000-31,000) among men. In 2023, an estimated 2.2 million (95% CI: 2,200,000-2,300,000) adults (15+ years) with HIV were living in Mozambique. District-level estimates highlighted areas of higher adult HIV prevalence and incidence in urban areas of key cities and ports, in the south, and along coastal districts in central Mozambique. Compared to men the same age, the distribution of HIV infections remains concentrated among women, particularly young women.

Conclusions: Mozambique continues to face a high burden HIV epidemic, with high HIV incidence associated with spatial heterogeneity. Prevention of new infections through women and young women-centred prevention programmes, treatment for men, and focusing interventions in urban areas, port cities, and coastal areas in central and southern Mozambique could contribute to reducing the HIV burden in Mozambique.

Keywords: HIV; Mozambique; Naomi model; Population‐based surveys; incidence; prevalence.