HIV – new vaccine, new hope?
In the news today:
What?
Researchers who carried out a trial of a new HIV vaccine in Thailand found the jab reduced the risk of being infected by nearly a third.
Why?
HIV infection causes AIDS. Although it may be possible to inhibit HIV infection from developing into AIDS, the best situation is to prevent people from becoming infected with the virus.
When?
This clinical trial began in October 2003 and studied more than 16,000 HIV-negative Thai men and women aged 18 to 30 judged to be at average risk of becoming infected.
How?
Half of the participants received four “priming doses” and two “booster doses” of the vaccine over six months. The other half received pacebo shots. All were given condoms, counselling and treatment for any sexually transmitted infections and were tested every six months for HIV. Any who became infected were given free treatment with antiviral medicines. Participants were followed for three years after vaccination ended.
Two different vaccines were used, each of which had been tested before and shown to be ineffective on its own. The priming vaccine was Alvac, which is based on bird virus canarypox genetically altered to express synthetic versions of three different HIV envelope genes. Canarypox cannot replicate in humans so is very safe. The booster vaccine was Aidsvax which consists of two different recombinant HIV gp120 envelope proteins.
The Good News
After 25 years of trying, this is the first vaccine scientifically proven to show some protection against HIV infection of humans. Although similar results have been obtained in animal studies, it has never before been possible to actually demonstrate that prevention of HIV infection (and hence AIDS) is possible in humans.
The Bad News
This candidate treatment will never come to the market. At a little over 30% effectiveness, it is not good enough. The significance of this story is that we now that protection against HIV is possible in practice, not just in theory. By studying how this vaccine works, researchers hope to produce more effective vaccines that will be used in humans, although that is at least several years away.
Related:
- Why is HIV a pathogen?
- How does HIV cause AIDS?
- Antibodies against persistent viruses
- Re-awakening old genes to help in the fight against viruses
- HIV is evolving rapidly to escape the immune system
Tags: Biology, Biotechnology, Health, HIV/AIDS, Medicine, Microbiology, Science, Vaccines, Virology, virus
I’m a little skeptical… There have been several promising vaccines in the pipes that have either failed or caused more harm than good.