Full results show AIDS vaccine is of modest help

Oct 20, 2009 By MARILYNN MARCHIONE , AP Medical Writer

(AP) -- Fresh results from the world's first successful test of an experimental AIDS vaccine confirm that it is only marginally effective and suggest that its protection against HIV infection may wane over time.

Yet the findings are exciting to scientists, who think that blood samples from the trial may show how to make a that does a better job.

The results also hint that the vaccine may work better in the general population than in those at higher risk of infection, such as gay men and intravenous drug users. It was the first time an vaccine was tested mostly in heterosexuals at average risk, and doctors have long known that how a person is exposed to HIV affects the odds of becoming infected.

"This study becomes a landmark. You can put it on a map and begin to figure out where you go from here," said Col. Jerome Kim, the U.S. Army doctor who co-led the trial.

Last month, researchers announced that a two-vaccine combination cut the risk of becoming infected with HIV by more than 31 percent in a trial of more than 16,000 volunteers in Thailand.

Full results, published online Tuesday by the and presented at a scientific conference in Paris, include two additional analyses that merely suggest the vaccine is beneficial, rather than providing definitive proof.

That's mostly because so few participants became infected - only 125 people, 10 times less than in previous HIV vaccine trials, said Dr. Anthony Fauci, director the National Institute of Allergy and Infectious Diseases, the study's main sponsor.

Critics had leaked one of the analyses last week, saying it showed the original results may have been a fluke. A California-based AIDS advocacy group criticized study leaders for not giving a fuller picture when they held their news conference last month.

"The bottom line is that those results are real," even though they are not good enough to justify using this vaccine now, said Dr. Alan Bernstein, executive director of the Global HIV Vaccine Enterprise, an alliance of governments, AIDS scientists, the World Health Organization and funders such as the Bill & Melinda Gates Foundation.

"We, for the first time, have evidence of protection, and the nitty gritty (arguments) to me don't matter a damn," Bernstein said.

Other scientists who, like Bernstein, had no role in the trial, agreed.

"It's a consistent story. There seems to be some effect. And I think it is an important study. It redirects the field to look at a different kind of vaccine and different kinds of immune responses" than what have been the focus in the past, said Dr. Lawrence Corey of the University of Washington. He heads the Trials Network, an international group of scientists who test vaccines.

The Thailand Ministry of Public Health conducted this trial, which used vaccines made from strains of HIV common in Thailand. They are ALVAC, made by Sanofi Pasteur, and AIDSVAX, originally developed by VaxGen Inc. and now held by the nonprofit Global Solutions for Infectious Diseases. The vaccines are not made from whole virus and cannot cause .

The combo was tested in HIV-negative Thai men and women ages 18 to 30 at average risk of becoming infected. Half received four doses of ALVAC and two of AIDSVAX over six months; the rest received dummy shots. All were given condoms and counseling, and were followed for three years after vaccination ended.

New infections occurred in 51 of the 8,197 given vaccine and in 74 of the 8,198 who received dummy shots. That worked out to a 31 percent lower risk of infection for the vaccine group.

In a smaller analysis of just the 12,452 participants who received all six shots exactly on schedule, there were 86 infections - 36 in the vaccine group and 50 in those given dummy shots.

Though not a statistically significant trend, the vaccine appeared nearly twice as effective among those at low or moderate risk of becoming infected, versus people who share needles, have contact with prostitutes or engage in other risky behaviors.

"Perhaps the requirements for protection against transmission in low-risk heterosexual persons are considerably different or less stringent," Dr. Raphael Dolin of Beth Israel Deaconess Medical Center in Boston wrote in an editorial published by the medical journal.

---

On the Net:

New England Journal: www.nejm.org

Vaccine conference: tinyurl.com/d235nn

Study information: www.hivresearch.org/phase3/factsheet.html

©2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Explore further: Research shows anti-HIV medicines can cause damage to fetal hearts

add to favorites email to friend print save as pdf

Related Stories

A world first: Vaccine helps prevent HIV infection

Sep 24, 2009

(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 ...

Puzzling results from HIV vaccine trial

Dec 03, 2007

A potential HIV vaccine that recently failed a clinical trial in the United States may increase some people's chance of catching the virus that causes AIDS.

Volunteers key to success of Thai vaccine trials

Sep 28, 2009

(AP) -- Nearly 16,000 Thais ignored the false rumors that they were being infected by the AIDS virus, and overcame their fears of becoming social outcasts to participate in the first HIV vaccine trials to ...

AIDS vaccine trial exceeds expectations

Sep 23, 2005

An experimental AIDS vaccine of Merck & Co. has exceeded expectations and led to a double enrollment in the trial to 3,000, researchers said.

AIDS experts go back to basics

Mar 27, 2008

The head of the U.S. agency in charge of AIDS research says scientists need to go back to basics to find a vaccine against the HIV virus.

Recommended for you

New study reveals why some people may be immune to HIV-1

Nov 20, 2014

Doctors have long been mystified as to why HIV-1 rapidly sickens some individuals, while in others the virus has difficulties gaining a foothold. Now, a study of genetic variation in HIV-1 and in the cells ...

Virus discovery could impact HIV drug research

Nov 20, 2014

A research team led by Portland State University (PSU) biology professor Ken Stedman has unlocked the structure of an unusual virus that lives in volcanic hot springs. The discovery could pave the way for better drugs to ...

UN warns over threat of AIDS rebound

Nov 19, 2014

South African actress Charlize Theron threw her weight Tuesday behind an urgent new UN campaign to end AIDS as a global health threat by 2030.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.