Two international trials of Merck & Co. Inc.’s experimental AIDS vaccine were stopped after researchers realized the vaccine did not prevent infection with the AIDS virus.
Instead, indications suggest that the vaccine may actually raise the risk of infection, though it cannot cause an HIV infection itself.
Now, Merck has announced that it will “unblind” the study, and let the thousands of volunteers know who received the active vaccine and who got a dummy shot.
Researchers have begun counseling volunteers that they could now be at a higher risk of contracting HIV.
The AIDS vaccine trials were conducted in the United States, Peru, Brazil, Dominican Republic, Haiti, Jamaica, Australia and South Africa.