HIV-1 is the most common type of human immunodeficiency virus. It primarily targets immune cells (especially CD4 T-cells) and, if left untreated, can gradually weaken the immune system over time. HIV-1 is the main cause of the global HIV epidemic and is the type most people refer to when they say “HIV”.

HIV-1 is a virus that infects and damages cells in the immune system. Over time, a decreasing number of CD4 T-cells can reduce the body’s ability to fight infections. Without treatment, HIV infection can progress to AIDS (acquired immunodeficiency syndrome), which is the advanced stage of HIV infection.
HIV-1 can be transmitted through exposure to infected blood, semen, vaginal fluids, and breast milk. Common transmission routes include unprotected sexual intercourse, sharing needles or syringes, and from mother to child during pregnancy, delivery, or breastfeeding. It is not spread through casual contact such as hugging, sharing utensils, or using the same toilet.
Self-tests like this one detect antibodies produced by the immune system in response to HIV-1 (and HIV-2). Antibodies are not always detectable immediately after exposure, which is why timing is important.
After a possible exposure, it may take time before antibodies reach detectable levels. During this “window period,” a test can be negative even if infection has occurred. If exposure is recent, repeating the test later and/or seeking medical advice for appropriate follow-up is important.
