Moderately age-disparate relationships dominate phylogenetically linked pairs involving young women with HIV in KwaZulu-Natal, South Africa
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Objectives
Young women aged 15-24 years bear a disproportionate burden of new human immunodeficiency virus (HIV) infections in sub-Saharan Africa. Age-disparate relationships with older men have been proposed as a major contributor to this pattern.
Methods
We conducted whole-genome sequencing of HIV in large cohort of individuals in KwaZulu-Natal, South Africa (the Vukuzazi cohort). Samples with viral loads >50 copies/mL were sequenced. Genomes passing quality control were grouped into clusters using maximum likelihood phylogenetic analysis. Potential transmission pairs were analyzed alongside participant age and sex data. A Bayesian random-effects model estimated transmission rates between demographic groups while accounting for population age-sex structure.
Results
Among 18,025 participants enrolled in 2018-2020, 6096 were HIV-positive. Sequencing yielded 1097 genomes, identifying 89 clusters containing 205 individuals and 73 likely male-female linked phylogenetic pairs. Across pairs, men were a median of 5 years older than women (interquartile range −1 to 12). Women aged <30 years paired with men aged a median of 7 years older, whereas among women aged ≥30 years men were typically younger. After accounting for population structure, the strongest signal for transmission was between women aged 25-29 years and men up to 4 years older.
Conclusion
Relative transmission rates were greatest with moderate age differences. Large intergenerational age gaps were not dominant.
Young women aged 15-24 years bear a disproportionate burden of new human immunodeficiency virus (HIV) infections in sub-Saharan Africa. Age-disparate relationships with older men have been proposed as a major contributor to this pattern.
Methods
We conducted whole-genome sequencing of HIV in large cohort of individuals in KwaZulu-Natal, South Africa (the Vukuzazi cohort). Samples with viral loads >50 copies/mL were sequenced. Genomes passing quality control were grouped into clusters using maximum likelihood phylogenetic analysis. Potential transmission pairs were analyzed alongside participant age and sex data. A Bayesian random-effects model estimated transmission rates between demographic groups while accounting for population age-sex structure.
Results
Among 18,025 participants enrolled in 2018-2020, 6096 were HIV-positive. Sequencing yielded 1097 genomes, identifying 89 clusters containing 205 individuals and 73 likely male-female linked phylogenetic pairs. Across pairs, men were a median of 5 years older than women (interquartile range −1 to 12). Women aged <30 years paired with men aged a median of 7 years older, whereas among women aged ≥30 years men were typically younger. After accounting for population structure, the strongest signal for transmission was between women aged 25-29 years and men up to 4 years older.
Conclusion
Relative transmission rates were greatest with moderate age differences. Large intergenerational age gaps were not dominant.
Date Issued
2026-08-01
Date Acceptance
2026-04-29
Citation
International Journal of Infectious Diseases, 2026, 169
ISSN
1201-9712
Publisher
Elsevier
Journal / Book Title
International Journal of Infectious Diseases
Volume
169
Copyright Statement
© 2026 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
License URL
Identifier
10.1016/j.ijid.2026.108759
Publication Status
Published
Article Number
108759
Date Publish Online
2026-05-07