The virus cannot be transmitted through the air by sneezing or coughing. But it's not who you are, it's what you do. High-risk behavior will leave you open to HIV infection, no matter who you are. Although it's easier for the receptive partner to be infected, research has shown that the virus can also move in the opposite direction, infecting the insertive partner. Unprotected, receptive anal and vaginal sex appear to be the most common routes of sexual transmission.
Oral sex is less risky, but it is possible to become infected orally.
Sharing needles with an infected person or injecting any substance with an unsterile needle is probably the most direct way to become infected. Needles used to take blood are sterile and individually packaged. They are also destroyed after use. Although there have been cases of infection in the past, it is now nearly impossible to become infected with HIV by receiving blood via a transfusion. Screening procedures to detect infected blood have been in place for several years.