The vaccine has successfully completed the first phase of tests among 40 Swedish HIV-negative volunteers, the Karolinska Institute in Stockholm said in a statement coinciding with World AIDS Day.
“It has been more effective than we thought it would be,” Eric Sandström, professor and head of clinical testing at the institute told AFP.
“We have also failed to find any vaccine-related side effects at all,” he added.
“There is every reason to be hopeful, even though the study is not finished,” Karolinska professor Britta Wahren who developed the vaccine said.
Trials for new vaccines undergo a long, three phase process. In the first phase, the formula is tested on a small group of volunteers to see primarily whether it is safe, but also to see whether it induces a response from the immune system.
After that it goes through progressively wider trials, among thousands of volunteers, to assess effectiveness.
DNA vaccines are an experimental technology in which one or more genes coding for specific antigens – surface proteins on the virus – are directly injected into the body.
The goal is that they induce an immune response so that the body’s defences recognize the virus if it ever enters the body.
“The technology is highly promising for producing simple, inexpensive and heat-stable vaccines,” the US-headquartered International AIDS Vaccine Initiative (IAVI) says.
However, there have been a lot of disappointments with this approach, said Sandström.
“There has been skepticism about whether it would in fact be possible to use DNA vaccines for HIV on humans. In that context our findings are really uplifting,” Sandström said.
The researchers are now planning on entering a second phase of testing in which a Modified Vaccinia Ankara (MVA) vaccine is used to try to boost immune response.
“There is much to indicate that the final result when the study is finished will be above our expectations,” Sandström said, adding that 38 of the subjects from the first phase of the study had already volunteered for the second phase.
The trial wraps up next May or June. The researchers hope to launch a third phase of tests in Tanzania to determine whether the vaccine actually limits the effects of the virus for those infected with HIV.
In the 24-year history of AIDS, only one vaccine has completed the full three-phase trial process – AIDSVAX – which was found to be a disappointing failure.
At the moment, more than 30 candidate AIDS vaccines are being tested in small-scale human clinical trials around the world, the majority of which began in the past four years in response to greater financial help.