A world first: Vaccine helps prevent HIV infection

Sep 24, 2009
FILE -In this May 15, 2006 file photo, AIDS/HIV patients spend a quiet afternoon at Wat Phrabatnampo AIDS hospice , in Lopburi, Thailand. Researchers in Thailand reported for the first time, an experimental vaccine has prevented infection with the AIDS virus, a watershed event in the deadly epidemic and a surprising result. The vaccine cut the risk of becoming infected with HIV by more than 31 percent in the world's largest AIDS vaccine trial of more than 16,000 volunteers in Thailand, researchers announced Thursday, Sept. 24, 2009 in Bangkok. (AP Photo/David Longstreath, File)

(PhysOrg.com) -- In an encouraging development, an investigational vaccine regimen has been shown to be well-tolerated and to have a modest effect in preventing HIV infection in a clinical trial involving more than 16,000 adult participants in Thailand. Following a final analysis of the trial data, the Surgeon General of the U.S. Army, the trial sponsor, announced today that the prime-boost investigational vaccine regimen was safe and 31 percent effective in preventing HIV infection.

"These new findings represent an important step forward in HIV vaccine research," says Anthony S. Fauci, M.D., director of the National Institute of Allergy and Infectious Diseases (NIAID), part of the NIH, which provided major funding and other support for the study. "For the first time, an investigational HIV vaccine has demonstrated some ability to prevent HIV infection among vaccinated individuals. Additional research is needed to better understand how this vaccine regimen reduced the risk of HIV infection, but certainly this is an encouraging advance for the HIV vaccine field."

"We thank the trial staff in Thailand and the United States for their years of effort in successfully conducting this study and the study participants and the people of Thailand for their long-standing support of HIV vaccine research," Dr. Fauci adds.

The Thai Phase III HIV vaccine study, also known as RV144, opened in October 2003. The placebo-controlled trial tested the safety and effectiveness of a prime-boost regimen of two vaccines: ALVAC-HIV vaccine (the primer dose), a modified canarypox vaccine developed by Sanofi Pasteur, based in Lyon, France, and AIDSVAX B/E vaccine (the booster dose), a glycoprotein 120 vaccine developed by Vaxgen Inc., and now licensed to Global Solutions for Infectious Diseases (GSID), based in South San Francisco, Calif. The vaccines are based on the subtype B and E HIV strains that commonly circulate in Thailand. The subtype B HIV strain is the one most commonly found in the United States.

Led by principal investigator Supachai Rerks-Ngarm, M.D., of the Thai Ministry of Public Health’s Department of Disease Control, the study was sponsored by the U.S. Army in collaboration with NIAID, Sanofi Pasteur and GSID. The trial, conducted in the Rayong and Chon Buri provinces of Thailand, enrolled 16,402 men and women ages 18 to 30 years old at various levels of risk for HIV infection. Study participants received the ALVAC HIV vaccine or placebo at enrollment and again after 1 month, 3 months, and 6 months. The AIDSVAX B/E vaccine or placebo was given to participants at 3 and 6 months. Participants were tested for HIV infection every 6 months for 3 years. During each clinic visit, they were counseled on how to avoid becoming infected with HIV.

In the final analysis, 74 of 8,198 placebo recipients became infected with HIV compared with 51 of 8,197 participants who received the vaccine regimen. This level of effectiveness in preventing HIV infection was found to be statistically significant. The vaccine regimen had no effect, however, on the amount of virus in the blood of volunteers who acquired HIV infection during the study.

"The Thai study demonstrates why the HIV vaccine field must take a balanced approach to conducting both the basic research needed to discover and design new HIV vaccines and, when appropriate, testing candidate vaccines in people," says Margaret I. Johnston, Ph.D., director of NIAID’s Vaccine Research Program within the Division of AIDS. "Both avenues provide critical information that will continue to help us better understand what is needed to develop a fully protective HIV vaccine."

NIAID and the collaborating partners are working with other scientific experts to determine next steps, including additional research of the RV144 vaccine regimen and the need to consider the impact of these new findings on other HIV vaccine candidates.

Individuals who acquired HIV infection while participating in the Thai trial have been provided access to HIV care and treatment, including highly active antiretroviral therapy based on the guidelines of the Thai Ministry of Public Health.

For more information about the Thai Phase III HIV vaccine trial, please see: www.hivresearch.org

Provided by National Institutes of Health

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User comments : 7

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SincerelyTwo
Sep 24, 2009
This comment has been removed by a moderator.
El_Nose
5 / 5 (4) Sep 24, 2009
I just don't get vaccination results -- were all of these people at risk of having sex with someone with AIDS?? were they married to someone with AIDS? you are saying that with two groups equally split down the middle that both sides should see the same number of people contract the virus... while statisticly sound in all practicallity you need more than one test on this scall to prove your results -- well at least to me.
Oigen
2.5 / 5 (6) Sep 24, 2009
The 31% is a percentage reckoned in relative terms which is the way these interminable studies where "hard data" is rarely quoted are reported. In this case actual numbers are reported so that one can calculate in absolute terms that there was only a difference of .28% between the groups. Put in another way, some 350 people would have to gobble pills over a period of years so that 1 person would ostensibly benefit a result which is hardly enough to get excited about.
Velanarris
5 / 5 (1) Sep 24, 2009
There is so much noise in this study and one can understand why.

I'm sure you wouldn't have many volunteers for a trial where part of the control was infecting the volunteer with a known strain of AIDS, however, the vaccines' efficacy is indeterminable in a study that doesn't do exactly that.
brianweymes
3.7 / 5 (3) Sep 24, 2009
No Oigen, that would only be correct if all the study participants were exposed to the AIDS virus, which obviously they were not.
nilbud
2.3 / 5 (3) Sep 24, 2009
In Thailand they would have no qualms whatsoever about human experiments and you can bet your ass the US army will adhere to "local laws" at the drop of a hat. Tuskegee was SOP.
Kato1524
2.8 / 5 (6) Sep 24, 2009
Not very scientific. Not very accurate. Too many variables to know for sure that the vacine has any effect on the results.

This study has no credibility. It must have been done by someone who used to work as a private investigator with the same accuracy and credibility in information.
MJW1230
not rated yet Sep 25, 2009
Oigen,
The results are presented accurately at 31% Both the odds ratio and relative risk are approx .68 (they approach each other when outcome is rare)