I went to the blood center to donate blood 13 days after having high-risk sex, and on the third day I received a message informing me that my blood was qualified.

RNA detection in plasma, also known as viral load detection, can generally detect HIV 9 days after infection. However, the general blood donation test should check for antibodies, so this passing test does not explain the problem. You still have to wait 6 weeks and then go to the CDC for a blood test. It is also recommended that you explain the situation to the blood donation center. Otherwise, if there is a virus in your blood, it may infect the next person, even if the blood is transfused back to you. Cross-infection may also occur on your body. This is a matter of conscience. If everyone does this, the blood in the blood bank will be unsafe and will cause severe bleeding or infection.