HIV is a virus that weakens the immune system. It passes from person to person through certain body fluids, such as blood, semen, vaginal fluids and breast milk, and from mother to child during pregnancy and birth, but not through everyday contact such as hugging, kissing or sharing food. Without treatment it can progress to AIDS, the most advanced stage of infection. There is no cure, but antiretroviral therapy stops the virus from multiplying and allows people to live full and healthy lives, and people whose virus can no longer be detected do not pass it on to sexual partners. WHO estimates that HIV has claimed 44.2 million lives since the start of the epidemic.
About 64% of people living with HIV live in the WHO African Region, and in sub-Saharan Africa women and girls account for six in ten new infections. Elsewhere, about two thirds of new infections occur among key populations, such as gay men and other men who have sex with men, sex workers, people who inject drugs and transgender people, and their sexual partners. Stigma, discrimination and punitive laws can keep them away from services. While new infections have fallen sharply in eastern and southern Africa since 2010, they have risen by 78% in the Middle East and North Africa, 25% in Latin America and 17% in eastern Europe and central Asia, and they are still rising in 21 countries. In 2025 international funding for HIV fell by 18%, the steepest drop in almost two decades, disrupting prevention, testing and community services in a number of countries.