The study was led by Professor Christophe Fraser, Moh Family Foundation Professor of Infectious Disease Epidemiology, at the Big Data Institute. The study used pathogen genome sequencing to characterise the general properties of people acting as sources of heterosexual transmission in Zambia.
A decade of available antiretroviral therapy progress in sub-Saharan Africa has dramatically improved HIV survival. Therapy also blocks transmission of the virus amongst those who are virally suppressed, but despite this, new infections persist. This study published in The Lancet Microbe, aimed to characterise infection sources and provide policymakers with the data for effective prevention strategies.
The HPTN 071 (PopART) trial took place in Zambia and South Africa between 2013 and 2018. A phylogenetics analysis (the study of the evolutionary history and relationships among or within groups of organisms, in this case HIV viruses) was conducted as an associated study in nine Zambian PopART communities. The study collected 7,124 blood samples to determine the precise genetic sequence of the HIV virus in them. The researchers found that men transmitted infections 2.09 times more than women, and that this ratio was much higher amongst men aged 25-39. Among 288 sources with drug resistance data, 52 carried viruses resistant to first-line available antiretroviral therapy.
Professor Fraser said ‘During the COVID epidemic, we all became familiar with virus genetics, which allowed us to see the emergence of variant after variant. In this study, the PANGEA-HIV consortium used this approach to study HIV, the virus that causes AIDS. PANGEA-HIV generated the largest dataset of HIV virus genomes in Southern and Eastern Africa to improve our understanding of the epidemic.
'Our findings inform public health in Zambian communities, where one in five adults are infected with HIV. It has been observed for a long time that men connect to healthcare less than women, and HIV more commonly affects women. Here, we quantified the effect of the gap in ART coverage, and found a disproportionate contribution to transmission from men aged 25-39. We also found that virus variants resistant to ART have been spreading extensively. Altogether, these findings point to a valuable contribution of this new tool, virus genomics, in understanding infectious disease epidemics.’
Dr Matthew Hall, Senior Researcher at the Big Data Institute and the author of the study said: ‘While we find a major role of younger men in transmission, there is otherwise nothing particularly notable about them. There is no particular group that is disproportionately driving new infections. This should guide interventions away from intense targeting of small subpopulations and towards general population interventions, with a particular eye on younger men.’