Interim findings of a phase 2b double-blind efficacy trial of an HIV vaccine candidate in an at-risk US population revealed that there was no indication that the vaccine was protective (Hammer SM et al. N Engl J Med. doi:10.1056/NEJMoa1310566 [published online October 7, 2013]).
The 2496 participants (98% were men, 2% were transgender women) were randomized to receive either vaccine or placebo. Although the vaccine produced cellular and humoral immune responses in participants, it offered no protection against infection, nor did it reduce mean viral load set points.
Slomski A. Halted HIV Vaccine Trial Assessed. JAMA. 2013;310(20):2139. doi:10.1001/jama.2013.283538