Does a normal healthy adult who has one sexual encounter with an HIV-infected person necessarily become infected with HIV? The answer, of course, is no. Having sex with an HIV-infected person does not necessarily result in the transmission of HIV, regardless of whether or not the sexual contact is safe. Whether or not HIV transmission will occur depends on whether or not both parties have taken safety measures, and whether or not the action during sex is too intense, resulting in greater damage to the genital mucosa. The two most important points are whether the infected person carries a large number of viruses that are particularly pathogenic and the immune status of the infected person’s body.