A large-scale analysis of nearly 1.4 million HIV-1 samples from 154 countries has shown that the geographic distribution of genetic variants of the virus continues to change. Researchers emphasize that the high genetic diversity of HIV makes it difficult to create a universal vaccine, and also affects the effectiveness of diagnostics and treatment.
The largest study of genetic variants of HIV-1 in the world to date has shown that the distribution of different subtypes of the virus between regions remains dynamic, creating additional challenges for the prevention and treatment of infection. The results of the work are published in the journal The Lancet Infectious Diseases.
As of 2024, an estimated 40.8 million people were living with HIV in the world. Although antiretroviral therapy has significantly improved life expectancy and helped reduce the transmission of the virus, in 2024, 630,000 people died from AIDS-related illnesses, and another 1.3 million people became newly HIV-positive. The researchers also note that the reduction in international funding in 2025 could jeopardize the achievements of recent years and further underscore the need for an effective vaccine that can provide broad protection against the virus.
One of the main obstacles to developing such a vaccine is the extraordinary genetic diversity of HIV. The most common type of the virus, HIV-1, has spread from Central Africa to other regions of the world since the beginning of the pandemic and has evolved into ten different subtypes. In addition, as a result of infection with several subtypes simultaneously, recombinant forms of the virus arise and actively circulate in a number of regions. This mosaic of HIV-1 variants is important not only for the development of vaccines, but also for the performance of diagnostic tests, monitoring of viral load and the effectiveness of antiretroviral treatment.
The study, led by the Global HIV Molecular Epidemiology Collaboration, analyzed HIV-1 subtype data from nearly 1.4 million samples collected in 154 countries between 1990 and 2024. The data was combined with UNAIDS estimates of the number of people living with HIV in each country, allowing them to track changes in the global prevalence of different variants of the virus over more than three decades.
The analysis showed that subtype C remained dominant in 2020–2024, accounting for nearly half of all HIV-1 cases worldwide—48.7%. It is most prevalent in South Africa and South Asia. Subtype A, which accounted for about 11.5% of global infections, was prevalent in East Africa, as well as Eastern Europe and Central Asia. Subtype B dominated in North America, Latin America, and Western and Central Europe, although its share on a global scale was only about 10%. The highest level of genetic diversity of HIV-1 was recorded by the researchers in Central Africa.
Although the overall proportions of the main HIV-1 variants remained relatively stable after 2000, the researchers found some important changes. In particular, in Western and Central Europe, as well as in East Asia, there was an increase in the proportion of recombinant forms of the virus. The authors note that the real prevalence of such forms may be even higher, since the analysis of only individual sections of the genome does not always allow them to be detected.
According to the researchers, continuous global monitoring of HIV genetic diversity remains critical. Understanding how different variants of the virus evolve and spread is necessary to improve diagnostic tests, monitor the development of drug resistance, and create vaccines and treatments adapted to specific genetic forms of HIV. As a next step, scientists plan to conduct a more detailed global analysis of recombinant HIV-1 variants and investigate the factors that determine changes in the genetic structure of the virus in different regions of the world.