The probability of getting AIDS from a single episode of high-risk sex is small, but it is still important to pay attention to protection, and if you have high-risk behavior, you need to take blocking medication in a timely manner. AIDS is a chronic systemic disease caused by human immunodeficiency virus infection, which can lead to damage to the human immune system, and in the advanced stages of the disease, patients will be combined with a variety of diseases. The main modes of transmission are sexual, mother-to-child, and blood. HIV transmission through sexual intercourse requires certain conditions to be met, i.e., the surface of the skin and mucous membranes are damaged during sexual intercourse, and HIV contained in bodily fluids, semen, or blood enters the human body through the damaged area and causes infection, so the chances of acquiring AIDS from a single episode of high-risk sexual intercourse are not high. Although the probability of getting AIDS from one high-risk sex act is small, it is still necessary to pay attention to protection, and taking blocking drugs within 72 hours of high-risk behavior can effectively reduce the risk of infection.