If the HIV test is negative at 4 months, you can completely rule out HIV infection. At present, the window period for HIV is usually around 4 weeks, and it is basically more accurate to take an HIV test after 4 weeks. In our country, the window period is advancing as the technology of HIV testing is changing day by day. The most commonly used HIV antibody test in China can detect HIV antibodies in the body about 3-4 weeks after infection. If HIV antigen-antibody combination test is used, it can be detected in the infected person’s body about 2-3 weeks after HIV infection. If the HIVRNA test is used, the virus can be detected in the infected person’s body about 7-10 days after infection and the diagnosis can be confirmed. Therefore, a 4-month test can completely rule out HIV infection.