As of 2024, an estimated 40.8 million people are living with HIV, a virus that attacks the body’s immune system and, if left untreated, leads to Acquired Immune Deficiency Syndrome (AIDS). Although antiretroviral therapy has improved life expectancy and reduced HIV transmission, 630,000 people died from AIDS-related illnesses and 1.3 million people became newly infected in 2024. Cuts to international funding in 2025 threaten to reverse gains made in recent years, heightening the need for an effective HIV vaccine that can offer universal protection.
Part of the challenge of developing such a vaccine relates to the global genetic diversity of the virus. HIV-1 is by far the most common type of HIV, and since the start of the pandemic in the early 1990s, it has spread from Central Africa to other parts of the world, diversifying into 10 different subtypes. In addition, co-infection with two or more HIV subtypes has resulted in ‘recombinant’ strains of HIV circulating in some regions. This patchwork of different HIV-1 variants has implications not just for vaccine development, but also for the efficacy of diagnostic and monitoring tests and antiretroviral treatment.
For this study published in The Lancet Infectious Diseases, researchers from the Global HIV Molecular Epidemiology Collaboration, which is led by Associate Professor Joris Hemelaar at the Nuffield Department of Population Health, contributed subtyping data from nearly 1.4 million HIV-1 samples collected between 1990 and 2024 from 154 countries. These data were combined with UNAIDS estimates of the number of people living with HIV in each country to map the global distribution of HIV-1 subtypes and recombinant strains over time.
Read the full story on the Nuffield Department of Population Health website.