Possible Outcomes of a
Vaccine to Prevent AIDS, continued

Scientists consider several possible favorable outcomes of a vaccine to prevent AIDS.

• A vaccine could prevent infection entirely- so-called sterilizing immunity. This is not achieved with any licensed vaccines in use.
• A vaccine could permit the person to become infected briefly, but would prepare the person's immune system to block continued infection and eliminate the virus. The childhood vaccines against measles, mumps, and polio work in this manner.
• A vaccine could delay the onset of AIDS for many years, perhaps by which time a more effective treatment could be available.
• A vaccine might not prevent AIDS in the infected person but could reduce the transmission of HIV to others.
• It is also possible that the vaccine would have no effect at all, or even make HIV disease progress more quickly.