According to the National Institute of Allergy and Infectious Diseases, the original Pave 100 study had planned to enlist 8,500 volunteers in the US, South America, the Caribbean and Africa. The most important aims of the study were to determine if the vaccine prevented HIV-1 infection and if vaccination leads to the decreased viral load if volunteers become infected by the human immunodeficiency virus in spite of vaccination.

US enrollment was scheduled to begin in October last year but it had to be put off due to the failure of Merck & Co's similar Phase II HIV vaccine trial, which was also supported by the NIAID, a component of the National Institutes of Health.

Later Pave 100 AIDS vaccine trial was reduced in scope to test the Vaccine Research Center (VRC) vaccine in 2,400 homosexual men in the United States. Deliberately, the men submitted to the test were to be circumcised and not to have prior neutralizing antibodies to adenovirus type 5 (Ad5), the cold virus used in the vaccine in the role of a carrier for the HIV genes. The revamping Pave 100 study would have tested the vaccine's impact on viral load and scrutinizing the immune responses to the vaccine and their effect on viral load.

The U.S. Centers for Disease Control and Prevention informed late on Tuesday that it will make public the new estimates of the number of Americans who become infected with the AIDS virus each year. Because it is believed the situation is alarming, CDC has been advised to disclose sooner the current situation. Therefore, it has been announced that the figures will be released on Aug. 3 in the Journal of Medical Association.