by Shaun Knittel -
SGN Staff Writer
For the first time, an experimental vaccine, RV 144, has prevented infection with the AIDS virus. According to researchers in Bangkok, Thailand, the vaccine cut the risk of becoming infected with HIV by more than 31% in the world's largest AIDS vaccine trial of more than 16,000 volunteers in the country.
Col. Jerome Kim, who helped lead the study for the U.S. Army, which sponsored it with the National Institute of Allergy and Infectious Diseases, said on September 24, "It's the first evidence that we could have a safe and effective preventive vaccine."
"It gives me cautious optimism about the possibility of improving this result," said the institute's director, Dr. Anthony Fauci. "But, this is not the end of the road."
Even though the benefit is modest, a marginally helpful vaccine could have a big impact. Every day, 7,500 people worldwide are newly infected with HIV; 2 million died of AIDS in 2007, the U.N. agency UNAIDS reports.
The Thailand Ministry of Public Health conducted the study, which used strains of HIV common in Thailand. It is important to note that whether such a vaccine would work against other strains in the U.S., Africa or elsewhere in the world, cannot be known at this time.
The study tested a two-vaccine combination of ALVAC and AIDSVAX in a "prime-boost" approach, where the first vaccine primes the immune system to attack HIV and the second strengthens the response.
ALVAC uses canarypox, a bird virus altered so it can't cause human disease, to ferry synthetic versions of three HIV genes into the body. AIDSVAX contains a genetically engineered version of a protein on HIV's surface. According to scientists, the vaccines cannot cause HIV.
When each vaccine was individually tested, it failed to prevent HIV infection. But when tested as a combo on HIV-negative Thai men and women ages 18 to 30 over the course of six months, no one knew the results would turn out this way.
New infections occurred in 51 of the 8,197 given the combo vaccine, and in 74 of the 8,198 who received a "dummy shot." That worked out to a 31% lower risk of infection for the vaccine group.
The vaccine had no effect on levels of HIV in the blood of those who did become infected.
It is unclear whether vaccine makers will seek to license the two-vaccine combo in Thailand. Before the trial began, the U.S. Food and Drug Administration said other studies would be needed before the vaccine could be considered for U.S. licensing.
"We are cautiously optimistic about the promising results made by the researchers in Thailand who tested the RV 144 experimental vaccine," said David Richart, executive director of Seattle's Lifelong AIDS Alliance. "These results shine a light on what has been a very long, dark tunnel for people living with HIV/AIDS and those who advocate on their behalf here in Seattle and worldwide."
Richart said this is the first positive sign in more than 20 years of HIV vaccine testing and is "a step in the right direction." He said Lifelong AIDS Alliance applauds the efforts of these researchers and of the many working tirelessly across the globe to "discover a vaccine that will truly eradicate HIV."
Despite this success, he said, "all of us working on behalf of those who have passed away from, or who are living with, HIV/AIDS understand that much more needs to be done."
"That's why 3,000 Seattleites will come together this Saturday to participate in the 23rd annual Seattle AIDS Walk, to increase awareness about the disease and raise the funds needed to continue the fight against HIV/AIDS," said Richart. "On behalf of the thousands of people we serve, Lifelong AIDS Alliance remains steadfast in its commitment to creating a world without HIV or AIDS."
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