Vaccines are among the most powerful and cost-effective disease prevention tools available.
A vaccine that could help prevent HIV infection or stop progression of the disease is the best hope to end the devastating AIDS pandemic. Vaccines have the potential to reach populations that otherwise have limited access to health care and prevention services. Vaccines have been pivotal in eliminating smallpox, nearly eliminating polio, and drastically reducing infectious diseases like measles and pertussis. A crucial question is whether a vaccine based on one strain of HIV would be effective for populations in which a different strain is predominant. Even after the release of a vaccine, there will be continued need for effective behavioral prevention programs.