What are the chances of contracting AIDS through sexual intercourse?

I believe everyone knows the great harm of AIDS. Once contracted, the patient's immune function will decline overall, resulting in various symptoms. The most important thing is that the disease is very difficult to treat. Until today, we can only control the disease, and there is no complete cure. Therefore, we must take measures to prevent AIDS. Everyone knows that sexual life can transmit AIDS, so what is the approximate probability of contracting AIDS through sexual behavior?

The chances of contracting HIV through sexual intercourse:

Can you get HIV through unsafe sex? Why are homosexuals more susceptible to AIDS?

The West began investigating the patterns of transmission through sexual contact in the late 1980s. Studies have shown that the risk of male-to-male transmission is the highest, followed by male-to-female, female-to-male, and female-to-female. Among different sexual behaviors, anal sex has the greatest risk of transmission, followed by unprotected vaginal sex, oral sex, and masturbation.

Data shows that the risk of male-to-male transmission is 1/10 to 1/1600, which means that if a healthy man has unprotected anal sex with an infected man ten times, he will be infected with HIV once. The most optimistic statistic is that it will only happen once in 1600 times. This is also the reason why gay men are more susceptible to HIV infection. Other risk rates are as follows: 1/200-1/2000 for male to female, 1/700-1/3000 for female to male, and there is no reliable statistical data on female to female transmission so far. It is estimated that in Thailand, the probability of women transmitting HIV to men through sexual intercourse is an average of 3-6 people infected for every 100 sexual contacts.

Sexual intercourse is the main route of HIV transmission in both developed and developing countries, but other ways of spreading the virus are more likely. According to various estimates, the probability of a mother transmitting the virus to her baby is 13%-48%. If the skin is accidentally pierced by a needle containing HIV-infected blood during a medical procedure, the possibility of infection is only one in 250, or 0.3%. However, if HIV-infected blood is transfused, the transmission rate is 90%-100%.

Another survey showed that HIV transmission varies greatly depending on the stage of infection of the infected person. Generally speaking, the disease is most contagious in the early stages, with a transmission rate of 1/10-1/20, because the virus content in the infected person's body is the highest at this time. The second peak of transmission is when the asymptomatic period is about to end and the clinical period is about to begin, with a transmission rate of 1/100-1/200. The transmission rate during the asymptomatic period is 1/1000.

A survey of gay men showed that during an unprotected anal intercourse, if the sexual partners are in the early stage of infection when they are most contagious, the likelihood of the recipient being infected is 10%-30%. In the middle stage of infection, the likelihood of the recipient being infected is only 0.01-0.1%. However, in the late stage of infection, the likelihood of infection rises back to 0.1-1%.