In 2009, results of the RV 144 trial conducted by several partners, including the NIH, the USMilitary HIV Research Program (USMHRP) and the Thai Ministry of Public Health, demonstrated modest protection by the ALVAC/gp120 candidate vaccine, but perhaps more importantly showed for the first time that an HIV vaccine was possible. The recent discovery of novel broadly neutralizing antibodies by a research consortium led by the International AIDS Vaccine Initiative (IAVI) and by the NIH Vaccine Research Center (VRC) have also generated new excitement. These recent scientific breakthroughs in the vaccine field have led to planning for new efficacy trials. One such trial would use a prime-boost candidate to attempt to improve upon the modest efficacy found in the RV 144 trial. Such a trial could cost from US$30 million to over US$100 million, depending upon trial size and the number of vaccine regimens being tested. In addition, the NIH and others are considering a passive antibody clinical trial as part of the development process for an antibody-based HIV vaccine.