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Source: ONE News -
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An experimental AIDS vaccine made using two older vaccines
protected volunteers, lowering the risk of infection by about a
third, US and Thai researchers reported.
The vaccine is a combination of Sanofi-Pasteur's ALVAC canary pox
vaccine and the failed HIV vaccine AIDSVAX, made by a San Francisco
company called VaxGen and now owned by the nonprofit Global
Solutions for Infectious Diseases.
It lowered the risk of HIV infection by 32% among 16,000
heterosexual Thai volunteers who had no special risk of AIDS
infection, the US and Thai government researchers said.
"We had 74 infections in the placebo group and 51 in the vaccine
group," Dr Jerome Kim, a US Army colonel at the Walter Reed
Army Institute of Research in Maryland, who helped lead the trial,
said in a telephone interview.
The result, almost completely unexpected, puzzled researchers, who
say they cannot figure out why the vaccine combination is
working.
The HIV virus was discovered in 1983.
It is also a triumph for its supporters, who went ahead with the
giant trial of 16,000 volunteers despite critics who said it was
unethical or a waste of money because the vaccine was so widely
expected to have no effect at all.
"Myself, like others, did not think there was a very high chance
that this would give any degree of efficacy," said Dr Anthony Fauci
of the US National Institute of Allergy and Infectious Diseases,
which helped pay for the study.
"But nonetheless, we went ahead with the trial and it was
controversial to go ahead with it."
Sanofi shares rose as much as 1.6% in early morning trade but gave
up the gains to fall 0.39% to 50.67 Euros by 0815 GMT, while the DJ
health index was down 0.54%.
"We see no commercial vaccine available for some time yet, but the
prospect has finally been raised (after 30 years of trying) that an
effective vaccine is possible," Michael Leacock, analyst at ABN
AMRO research said.
More extensive work is needed before a vaccine is suitable for
regulatory approval, he said.
Further muddying the waters of the trial result, people who got the
vaccine and who became infected anyway had just as much virus in
their blood and just as much damage to their immune systems as HIV
patients who went unvaccinated.
This means the vaccine helps to prevent infection but does nothing
to affect the virus once it is in the body.
"Although the level of protection that we saw was clearly modest,
the study is a major scientific advance," Kim said.
Vaccine is possible
"It is the first evidence that the development of a safe and
effective vaccine is possible. Although we don't have all the
answers now, it does have important implications for the future of
HIV vaccine design."
Kim stressed that the vaccine may not work in the people and places
where HIV is most common - in Africa, among men who have sex with
men and among injecting drug users.
"The vaccine was tested in Thailand and it is really specific for
the strains that are circulating in Thailand now," Kim said.
Fauci said the Thai findings did not suggest whether any of these
other dozens of other HIV vaccine trials should be dropped, or
pursued more actively.
"I know people are going to be asking the question, should we be
using it right away?" Fauci said.
But he and Kim said the researchers need to study the data, to see
why it protected some people.
Both also noted that the vaccine was formulated specifically to
work against two subtypes of the human immunodeficiency virus - E,
which circulates in Thailand and Southeast Asia, and B, which is
common in the United States and Europe.
In a statement, Sanofi-Aventis Chief Executive Chris Viehbacher
said that the company would continue its research into HIV by
partnering with academia, governments, non-governmental
organisations and other vaccine makers.
The 16,000 volunteers in the trial got six immunizations over six
months, four with ALVAC and two with AIDSVAX.
ALVAC is a genetically engineered canarypox virus that has spliced
into it synthetic versions of three HIV genes.
AIDSVAX is made using two versions of one HIV gene, one from the
B subtype and one from the E subtype.
The AIDS virus infects an estimated 33 million people globally and
has killed 25 million since it was identified in the 1980s.
It affects immune cells called T-cells.
Cocktails of drugs can control the virus but there is no cure.
In 2007, Merck & Co ended a trial of its vaccine after it was found not to work, and in 2003, AIDSVAX used alone was found to offer no protection, either.
