They only shut studies like this down for a very good reason
Feds shut down clinical trials for HIV vaccine, citing safety
"Independent safety experts ordered the halt earlier this week, after finding that those who received the vaccine ? as opposed to those who received the placebo ? faced a slightly bigger chance of contracting HIV, human immunodeficiency virus, L.A. Times said. HIV is the virus that causes AIDS."
http://www.washingtontimes.com/news/...ccine-citing-/