WHAT IS AN HIV VACCINE? A preventive HIV vaccine is a substance that teaches the body’simmune system to recognize and protect itself against HIV, thevirus that causes AIDS. HIV vaccines currently being tested inhumans are made from man-made materials that CANNOTcause HIV infection. Scientists believe that an effective HIV vaccine, given before exposureto HIV, could have a number of possible outcomes. These include: ■ Preventing infection in most people ■ Preventing infection in some people ■ Preparing a person’s immune system to block continued infection and eliminate the virus (vaccines against measles,mumps and polio work this way) ■ Delaying or preventing the onset of illness or AIDS The long-term goal is to develop a vaccine that is 100 percent effectiveand protects everyone from infection. However, even if a vaccine onlyprotects some people, it could still have a major impact on controllingthe epidemic. A partially effective vaccine could decrease the numberof people who get infected with HIV; those people, in turn, would notpass the virus on to others. Even when an HIV vaccine is developed,education and other prevention efforts will be needed so that peoplecontinue to practice safe behaviors.