An investigational HIV vaccine regimen tested in Thailand has been shown to reduce new infections by 31%.
The placebo-controlled study, consisting of a prime vaccine and three booster shots, was conducted in more than 16,000 Thai citizens who were HIV-negative at baseline. After a 3-year follow-up period, infections occurred in 74 of those who received placebo and 51 of those who received the active vaccine—a 31% rate reduction, according to a statement issued by Global Solutions for Infectious Diseases, the South San Francisco-based company that produces the booster dose.
There were no significant safety concerns noted at any of the six safety monitoring points during the trial. The RV144 trial is the first HIV vaccine study to show significant disease reduction, Dr. Anthony S. Fauci said in a statement issued by the National Institutes of Health.
The vaccine and booster were based on the subtype B and E HIV strains, which commonly circulate in Thailand.
The trial comprised noninfected volunteers aged 18-30 years who were considered at risk of contracting HIV; 40% of the population were women.
Participants received HIV protection counseling. They then received the active vaccine or placebo; these were administered again at months 1, 3, and 6. The booster or placebo was also give at months 3 and 6. Subjects were tested for HIV infection every 6 months for 3 years.
The vaccine did not meet its secondary end point, failing to reduce the amount of HIV circulating in those who became infected during the trial. But because of its success in reducing incident infections, investigation into the prime-boost regimen will continue, the U.S. Military HIV Research Program said in a statement.
The cosponsors of the RV144 trial are the United States Army Medical Research and Material Command, the National Institutes of Allergy and Infectious Diseases, and the Thailand Ministry of Public Health.