During a median follow-up period of 1. No HIV transmissions occurred. The investigators concluded that the risk of HIV transmission through vaginal intercourse in these circumstances was effectively zero Rodger. When HIV is not suppressed by antiretroviral treatment, vaginal intercourse without a condom is a highly efficient route of HIV transmission because high concentrations of HIV can occur in semen and vaginal fluids, and because the genital tissues are very susceptible to infection. This allows the virus to reach the inner vaginal lining, which is rich in immune cells through which it can establish systemic infection. Cells located beneath the surface of the cervix are particularly vulnerable to HIV infection, especially during adolescence and during a woman's first pregnancy, or due to infection with human papillomavirus and chlamydia.

Vaginal sex intercourse involves inserting the penis into the vagina. Some sexual activities are riskier than others for getting or transmitting HIV. Activities like oral sex, touching, and kissing carry little to no risk for getting or transmitting HIV. In addition to HIV, a person can get other sexually transmitted diseases STDs like chlamydia and gonorrhea from vaginal sex if condoms are not used correctly.

And with the right precautions, even that most intimate of connections — conceiving a child together — can safely be accomplished. One way to address the anxiety about infecting a partner is to understand the exact level of risk involved with different types of sexual activity. Among heterosexuals, vaginal intercourse is a common route of HIV transmission, with the woman at greater risk for HIV infection than the man.