Possible Vaccine Outcomes

It is important to realize that scientists are still learning how vaccines might work to prevent HIV infection. An HIV vaccine may be totally successful in preventing any infection in vaccinated people, providing what is known as "sterilizing immunity." Sterilizing immunity may be possible in 100% of the population, or perhaps only in certain groups. In another scenario, a preventive vaccine may not prevent primary infection, but may decrease the possibility of HIV transmission from an infected person who has been vaccinated to another person. Yet another possibility is that a vaccine may not prevent infection entirely, but may slow the course of infection when it occurs. In this case, even if a vaccinated person becomes HIV infected, the vaccine helps that person remain healthier longer. The following list provides details about the variety of ways that scientists believe a preventive HIV vaccine might work.