The odds of having sex with a person of the opposite sex without wearing a condom, whose partner is living with HIV, may be 1 in 1000, with data from the Merck Diagnostic and Treatment Manual. However, according to the 2018 edition of the Chinese HIV diagnosis and treatment guidelines, the risk of infection from mucosal exposure is about 0.9 out of 100, which is close to 1 in 1000. This probability is an estimate and depends on the size of the exposure to HIV in body fluids. If the risk of infection is higher in early or progressive stages of HIV infection, the risk of infection will be higher. The risk of infection is also increased if there is a wound or breakage and exposure to these body fluids containing HIV.