HIV affects people of every age, gender, and background, but the burden falls unevenly. Of the roughly 41 million people living with HIV worldwide in 2024, 53% are women and girls, about 1.4 million are children under 15, and a growing share (26%) are adults over 50. The virus does not discriminate biologically, but patterns of transmission, access to prevention, and social vulnerability create sharp disparities across populations and regions.
Women and Girls Bear a Disproportionate Burden
More than half of all people living with HIV globally are women and girls. This is driven largely by what happens in sub-Saharan Africa, where gender gaps in infection rates are stark. Among adolescents aged 15 to 19 in the region, 80% of new HIV infections occur in girls. Young women in southern Africa face six times the HIV risk of young men their age; in eastern Africa, the ratio is three to one.
Several factors converge to create this disparity. Biologically, receptive vaginal intercourse carries a higher per-exposure risk than insertive intercourse. But biology is only part of the picture. In many high-prevalence settings, adolescent girls are more likely to have older sexual partners, less likely to negotiate condom use, and more vulnerable to sexual violence. These dynamics compound to make young women one of the most affected groups worldwide.
Key Populations and Transmission Risk
Globally, certain groups account for a large and growing share of new infections relative to their population size. In 2022, men who have sex with men (MSM) accounted for an estimated 20% of all new adult HIV infections worldwide, nearly double the 11% share from 2010. Sex workers made up about 7.7% of new infections (stable over the same period), and people who inject drugs accounted for 8%, up from 6.8%.
The biological reasons behind these patterns come down to transmission probability. Per single exposure, receptive anal intercourse carries roughly a 1.4% chance of HIV transmission, making it the highest-risk sexual act. By comparison, receptive vaginal intercourse has an estimated risk of about 0.08% per act, and sharing a needle during injection drug use falls in between at about 0.63%. These are per-act averages; actual risk varies with viral load, presence of other infections, and whether prevention tools like condoms or pre-exposure prophylaxis (PrEP) are used.
Transgender women also face elevated risk, contributing about 1.1% of global new infections in 2022. While that number sounds small in percentage terms, it represents a rate of infection far out of proportion to population size, driven by overlapping vulnerabilities including stigma, economic marginalization, and barriers to healthcare.
Geographic Concentration in Sub-Saharan Africa
Sub-Saharan Africa remains the epicenter of the global epidemic. The region is home to the majority of people living with HIV despite having a fraction of the world’s population. Prevalence rates in countries like Eswatini, Lesotho, and South Africa remain among the highest on earth, often exceeding 20% of adults.
Outside Africa, HIV is concentrated in specific communities rather than spread broadly across the general population. In Western Europe, North America, and parts of Asia, the epidemic is heavily driven by transmission among MSM, people who inject drugs, and their sexual partners. This distinction matters because it shapes how prevention resources are most effectively targeted.
Racial and Ethnic Disparities in the United States
Within the U.S., the epidemic is heavily shaped by race and ethnicity. Black/African American and Hispanic/Latino people together accounted for 70% of estimated new HIV infections in 2022, despite making up a much smaller share of the total population. These disparities are not explained by individual behavior. They reflect structural factors: segregation, poverty, unequal access to healthcare, and gaps in prevention services.
The gap in PrEP access illustrates this clearly. Among the estimated 1.1 million Americans with indications for PrEP, about 44% were Black and 25% were Hispanic. Yet among those actually prescribed PrEP in 2016, nearly 69% were white, while only 11% were Black and 13% were Hispanic. That mismatch between need and access is one of the clearest examples of how systemic inequality sustains the epidemic in communities of color.
Poverty as a Driving Force
Income and neighborhood poverty are strongly linked to HIV diagnosis rates. A study of New York City ZIP codes found a clear gradient: areas with the lowest poverty had a median HIV diagnosis rate of about 14 per 100,000 people, while the highest-poverty neighborhoods had a rate of 76 per 100,000, more than five times higher. The association held after accounting for racial composition, education levels, and age distribution.
The relationship was especially pronounced for women. Females living in very high-poverty neighborhoods had HIV diagnosis rates more than six times those of women in low-poverty areas. For men, the ratio was about 2.4 times. Poverty creates conditions that amplify HIV risk in multiple ways: reduced access to testing and treatment, housing instability, survival sex work, higher rates of untreated sexually transmitted infections, and limited availability of prevention tools like PrEP and clean syringes.
Children and Mother-to-Child Transmission
About 1.4 million children under 15 are living with HIV globally. Nearly all pediatric infections result from mother-to-child transmission, which can occur during pregnancy, labor, delivery, or breastfeeding. Without treatment, the risk of a mother passing HIV to her baby ranges from 15% to 45%.
Antiretroviral therapy during pregnancy dramatically reduces that risk. Each additional week a pregnant woman takes treatment before delivery lowers the odds of transmission by roughly 5.6%. With early, effective treatment, the risk drops to below 1%. The challenge is ensuring that all pregnant women living with HIV are diagnosed and started on treatment early enough. In high-income countries, mother-to-child transmission has been nearly eliminated. In parts of sub-Saharan Africa, gaps in prenatal care mean thousands of children are still infected each year.
The Growing Population Over 50
One of the less recognized shifts in the epidemic is the aging of the HIV-positive population. As of 2024, about 26% of all people living with HIV are 50 or older. This is partly a success story: effective treatment means people diagnosed decades ago are living into older age. But it also reflects ongoing new infections in older adults, who are less likely to be tested, less likely to use condoms, and often overlooked by prevention campaigns.
Aging with HIV brings its own set of challenges. People living with the virus face higher rates of cardiovascular disease, bone loss, kidney problems, and certain cancers compared to their HIV-negative peers. Long-term antiretroviral therapy contributes to some of these risks, and the chronic inflammation associated with HIV accelerates aspects of aging. This means that the healthcare needs of people living with HIV increasingly overlap with the concerns of geriatric medicine, not just infectious disease.