Age patterns of HIV incidence in eastern and southern Africa: a modelling analysis of observational population-based cohort studies

Abstract

Background As the HIV epidemic in sub-Saharan Africa matures, evidence about the age distribution of new HIV infections and how this distribution has changed over the epidemic is needed to guide HIV prevention. We aimed to assess trends in age-specific HIV incidence in six population-based cohort studies in eastern and southern Africa, reporting changes in mean age at infection, age distribution of new infections, and birth cohort cumulative incidence. MethodsWe used a Bayesian model to reconstruct age-specific HIV incidence from repeated observations of individuals' HIV serostatus and survival collected among population HIV cohorts in rural Malawi, South Africa, Tanzania, Uganda, and Zimbabwe, in a collaborative analysis of the ALPHA network. We modelled HIV incidence rates by age, time, and sex using smoothing splines functions. We estimated incidence trends separately by sex and study. We used estimated incidence and prevalence results for 2000-17, standardised to study population distribution, to estimate mean age at infection and proportion of new infections by age. We also estimated cumulative incidence (lifetime risk of infection) by birth cohort.Findings Age-specific incidence declined at all ages, although the timing and pattern of decline varied by study. The mean age at infection was higher in men (cohort mean 27•8-34•6 years) than in women (24•8-29•6 years). Between 2000 and 2017, the mean age at infection per cohort increased slightly: 0•5 to 2•8 years among men and -0•2 to 2•5 years among women. Across studies, between 38% and 63% (cohort medians) of the infections in women were among those aged 15-24 years and between 30% and 63% of infections in men were in those aged 20-29 years. Lifetime risk of HIV declined for successive birth cohorts.Interpretation HIV incidence declined in all age groups and shifted slightly to older ages. Disproportionate new HIV infections occur among women aged 15-24 years and men aged 20-29 years, supporting focused prevention in these groups. However, 40-60% of infections were outside these ages, emphasising the importance of providing appropriate HIV prevention to adults of all ages.Funding Bill & Melinda Gates Foundation.

Frequency of Human Immune Deficiency Virus (HIV) Infections at Tertiary Care Hospital of Karachi from 2017-2019

“…The current study reported male predominance having HIV with a mean age group of 30.39±10.162, as endorsed by another study 10 . Sindh showed the highest prevalence in the current study with a predominance in the Malir district.…”

“…The distribution of places among HIV cases directly corresponds to the national data 8 . The recent outbreak of HIV in Sargodha and Larkana represents a very distressing situation 10 . The human immunodeficiency virus (HIV) is a worldwide threat.…”

The Effect of HIV Programs in South Africa on National HIV Incidence Trends, 2000–2019

“…Our results suggest that VMMC and condom promotion have had more impact on HIV incidence at younger ages than at older ages, resulting in a shift in the age distribution of incidence toward older ages, consistent with other studies. 41,42 However, the change in age distribution is also partly the result of the natural dynamics of the epidemic: as people living with HIV age, they generate higher incidence rates at older ages. This is especially true for men: the 45% increase in HIV incidence in women aged $50 years over the 2000-2019 period is largely because of HIV-positive men aging into the $50-year age group.…”

A mixed-methods, exploratory, quasi-experimental evaluation of a radio drama intervention to prevent age-disparate transactional sex in Tanzania

“…Adolescent girls and young women account for 32% of new HIV infections in Eastern and Southern Africa despite constituting only approximately 10% of the population (3) and are 2.5 times more likely to contract HIV than their male peers (4). Although HIV prevalence has been steadily decreasing in the region, reductions are significantly slower among adolescent girls and young women than other demographic groups (3,5). Age-disparate transactional sex has also been associated with other negative sexual and reproductive health, developmental and social outcomes including early/forced marriage, sexual coercion, unplanned pregnancy, unsafe abortions, school dropout and violence (3,4,(6)(7)(8).…”