 Then, another group, infected with a second strain of HIV, A244, was discovered in 1995, and a revised, bivalent version of the vaccine was produced that combined elements of both MN and A244.Phase I and Phase II tests of the first version were promising, showing excellent safety in chimpanzees and humans and provoking production of HIV MN and A244 antibodies in 99% of human volunteers.VaxGen's leadership enthusiastically applied to the U.S. Food and Drug Administration (FDA) for permission to undertake Phase III studies in the U. S. on large numbers of at-risk volunteers.