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A study by researchers at Oxford Population Health has presented the most comprehensive analysis to date on the global and regional distribution of HIV-1 variants, highlighting significant trends and changes over the past decade. The study is published in The Lancet Microbe.

Human immunodeficiency virus (HIV) is a significant global health issue with an estimated 40 million people living with the disease globally. HIV-1 is the most common type of HIV but the extensive genetic diversity within this variant poses a major challenge to the development of an effective vaccine and means that better treatment and prevention strategies are urgently required. Understanding the distribution of different HIV-1 genetic variants can be used to inform the allocation of resources for HIV prevention and treatment.

The researchers looked at 1,044 datasets, encompassing HIV-1 subtyping data from 653,013 people living with HIV across 122 countries from 2010 to 2021. The proportions of HIV-1 subtypes, circulating recombinant forms (CRFs)*, and unique recombinant forms (URFs) in each country were weighted by UNAIDS estimates of the numbers of people living with HIV in each country to obtain regional and global prevalence estimates.

Key findings:

  • In 2016-2021, HIV-1 subtype C emerged as the most prevalent globally, accounting for 50.4% of infections.
  • Subtype A and B followed, with 12.4% and 11.3% of global infections, respectively.
  • Increases were observed in the proportions of subtype A (+0.9%), subtype C (+3.4%), and CRF07_BC (+0.4%), decreases in subtype D (-0.5%), subtype G (-0.8%), CRF02_AG (-0.8%), other CRFs (-0.7%) and URFs (-2.4%).
  • The global proportion of infections attributed to recombinant forms of HIV decreased from 21.6% in 2010‒2015 to 19.3% in 2016‒2021. This decrease was observed across various regions, indicating a shift in the genetic landscape of HIV-1.
  • Each global region displayed differences in the prevalence of the different HIV-1 variants, underscoring the need for tailored approaches to HIV management. For instance, subtype C was predominant in Southern Africa, while subtype B was more common in Western and Central Europe and North America.

Joris Hemelaar, Associate Professor at Oxford Population Health and senior author of the paper, said ‘The fight against HIV is not one-size-fits-all; it’s a global effort that requires tailored strategies to effectively combat different HIV-1 variants in diverse populations. mRNA vaccines offer a highly adaptable platform for developing variant-specific HIV vaccines. However, their success depends on continued and enhanced surveillance of HIV-1 variants worldwide. Monitoring changes in the prevalence of different subtypes and recombinant forms can help detect emerging trends and inform public health responses.’

The researchers call upon research funders, health organisations, governments, and the global research community to intensify their efforts in combating the HIV pandemic. Continued investment in surveillance and vaccine research is essential to adapt to the evolving genetic landscape of HIV-1 and to ultimately develop effective, targeted vaccines to address it.

*Recombinant forms of HIV occur when a person is infected with more than one type of HIV.