Although the 31 percent reduction in rates of infection was modest, Col. Jerome H. Kim, a doctor who manages the U.S. Army's HIV vaccine program, called the finding statistically significant. And, he added, it's "first evidence that we could have a safe and effective preventive vaccine," AP reported.
The Thais chosen for the study were a cross-section of that country's young adult population, not just high-risk groups such as intravenous drug users or sex workers, Kim added.
According to the study, there was a non-significant trend that suggested that low-risk individuals gained more protective benefit from the vaccine than those at higher risk, such as intravenous drug users who shared needles, or people who had contact with prostitutes.
"Perhaps the requirements for protection against transmission in low-risk, heterosexual persons are considerably different or less stringent than those in high-risk subjects," Dr. Raphael Dolin, of Beth Israel Deaconess Medical Center and Harvard Medical School in Boston, wrote Tuesday in an accompanying editorial in the journal.
Dorin also noted that although the trial lasted three years, "there is a suggestion that more of the effect might have occurred during the first year." More study needs to be done to determine if, in fact, the shot's benefits fade with time, he said.
The chief usefulness of the ALVAC-AIDSVAX vaccine will probably be what it can teach infectious-disease researchers about what is happening in the immune system when a person is even somewhat protected against HIV.
To learn more about HIV and AIDS, visit the U.S. Centers for Disease Control and Prevention.
SOURCES: Oct. 20, 2009, New England Journal of Medicine; Associated Press; The N
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