Analysis: Time To Quit On AIDS Vaccine
Toronto (UPI) Aug 19, 2006
For more than 20 years, scientists have been searching for the vaccine they believe can end the 25-year-old AIDS pandemic, a worldwide health disaster that has claimed more than 25 million lives. As Catherine DeAngelis, editor of the Journal of the American Medical Association, says, "That landmark means AIDS has taken more lives than were lost during the bubonic plague of the Middle Ages."
However, despite the fervent calls for vaccines, the last two decades have only seen vaccine failures. At the 16th International AIDS Conference in Toronto last week, the frustration over the lack of a vaccine let Jules Levin, a long-time AIDS activist, and executive director and founder of the New York-based National AIDS Treatment Action Project, to utter what some in the AIDS movement would call "heresy."
"We are not going to find a vaccine for human immunodeficiency virus (HIV). There will never be an AIDS vaccine," Levin told United Press International. "We are only wasting a lot of resources. It's time we stopped spending this money on the vaccine and start looking at other forms of prevention."
Heresy, indeed, said another long-term AIDS activist, David Scondras, the Boston, Mass.-based editor of the treatment and action newsletter "A Search for the Cure".
"I don't think Jules' comments represent what most of us believe. We cannot give up on a vaccine," he told UPI. "Instead, it's time to test all these different ideas that people are coming up with all the time. We don't need huge cohorts of people to do these tests, either."
Scondras said groups of sero-discordant couples could be recruited to be the test candidates. A sero-discordant couple consists of one person who, in this context, has been infected with the HIV virus and a partner who is HIV-negative, or not infected.
Despite the high risk that unprotected sex will eventually result in transmitting the incurable virus to the other partner, many couples continue to engage in risky sexual activity. A relatively few of these couples would be able to determine if a candidate vaccine worked, Scondras explained.
In a population-based vaccine trial, huge numbers of people at risk of HIV-infection because they engage in sexual practices that might bring them in contact with an infected person are required to prove the effectiveness of the vaccine. The ethics and financial problems involved in these large scale tests would prohibit testing multiple candidate vaccines.
Levin may be among the minority of those raising their voices about whether vaccines should be pursued. However, the fervor for a vaccine has decidedly diminished.
In his closing remarks to the conference, Stephen Lewis, the Canadian diplomat who is the outgoing United Nations special envoy for HIV/AIDS in Africa, and regarded by many as representative of the moral center of the AIDS battle, barely mentioned vaccines.
"To be certain, there can be no flagging in the dogged quest for a vaccine, but it would appear that where preventative technologies are concerned, the microbicide is first in line," the silver-tongued orator said. When that is the only mention of an AIDS vaccine in a closing speech by Stephen Lewis, it is obvious that many people are rethinking the priority of vaccine research.
Lessons learned over the years in vaccine attempts, however, may be helping scientists construct a vaccine that will work. The virus is not easily identified as a pathogen by the human immune system and mounting antibody attacks on the microbe has failed multiple times.
Peter Lara, an AIDS researcher, says the virus avoids detection by the immune system because it presents decoys to the immune system. The immune cells in the body attack the decoys, but never are unable to penetrate the virus itself.
Lara, who works for Biological Mimetics, Inc. in Fredrick, Md., is trying to devise an antibody that will strip the decoys away from the virus, exposing it to normal attack by the immune system. He is still working on animal models of the disease with his "immune refocusing" technology, he said during a press briefing at the AIDS conference, and human studies are still in the future.
Biological Mimetics' vaccine is one of dozens being explored, few of which are close to large-scale human testing.
The hundreds of millions of dollars being invested in vaccines would be better diverted to other areas; namely, the low-hanging fruit of prevention, said Levin. He and Scondras concur that microbicides that could be used to kill the virus during sexual intercourse is the best bet to prevent spread of the disease, especially among women who appear to be disproportionately infected through heterosexual contacts.
However, even the most optimistic researchers suggest that a microbicide is still at least five years from the marketplace, Lewis stated.
Another area of prevention involves the use of antiretroviral drugs such as tenofovir (Viread) that would be taken prior to engaging in risky sexual activity. Several studies of this "Pre-Exposure Prophylaxis (PrEP)" are underway.
But doctors and activists also argue that a vaccine is still needed because large numbers of women who are raped have no opportunity to use a microbicide or take the pills in advance of an attack.
Stefano Vella, director of the drug research and evaluation department of the U.S. National Institutes of Health's counterpart in Rome, Italy, the Instituto Superiore di Saniti, was clearly vexed discussing vaccine development against HIV. "We clearly do need to go ahead and find a vaccine," he told UPI, "but perhaps we need to be looking more for a therapeutic vaccine rather than a preventive vaccine."
A preventive vaccine -- the form of treatment that is considered the Holy Grail -- would stop the virus from infecting humans, effectively ending the epidemic that now affects 38.6 million people around the globe, mostly in developing countries.
A therapeutic vaccine would help people living with HIV keep the virus at bay and prevent the microbe from wiping out people's immune systems, and subsequently permitting the opportunistic infections -- such as pneumonia, diarrhea and rare cancers -- that are the hallmarks of AIDS and what actually kills patients.
The therapeutic vaccine, Vella said, would possibly allow people to be treated with a yearly inoculation instead of daily drug therapy, a lifelong treatment burden and expense.
"I personally don't think we are spending enough money on vaccine development," said Lieve Fransen, a representative of the European Commission at the AIDS conference and vice chair of the Global Fund for the Treatment of AIDS, Tuberculosis and Malaria.
"In my personal opinion, vaccine research has been delayed too long," she told UPI. "If we are really going to break the epidemic we are going to need a vaccine as well as microbicides. If we as a society can send a man to the moon, then we must be able to find and develop a vaccine. We have not spent enough attention on the vaccine, nor have we spent enough money to find one."
Source: United Press International
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