AIDS vaccines experts are confused, dismayed

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AIDS vaccines experts confused, dismayed

November 12, 2007 - 12:24PM

AIDS vaccine researchers are worried about the future of their field

after learning an experimental HIV vaccine not only does not work, but

just might make recipients more susceptible to infection with the AIDS

virus.

They are worried about their volunteers and the future of AIDS

vaccines in general. And they are worried because they cannot

understand how a vaccine would make a person more vulnerable.

Researchers from Merck & Co., which makes the vaccine, and the

National Institute of Allergy and Infectious Diseases, which is

helping develop it, said they believe a type of common cold virus used

as the basis of the vaccine may somehow have made their volunteers

more susceptible to HIV.

They are meeting this week in Seattle to hash through the data and

figure out what happened.

This is what they know: Out of 1,500 people vaccinated, 82 became

infected with the AIDS virus. Of these, 49 got the vaccine and 33 got

a placebo shot.

While they are counselling volunteers that they may have raised their

own risk of becoming infected, they are also trying to figure out what

happened.

" The data are disappointing and puzzling but we don't have definitive

answers, " Dr. Lawrence Corey of Fred Hutchinson Cancer Research Centre

in Seattle, who was organising the trial, told reporters.

Only one woman in the trial became infected with HIV. The rest were

men having sex with other men, and it was the men who started out with

the highest immune response to the adenovirus 5 common cold bug used

to make the vaccine who were the most likely to become infected with

the AIDS virus.

But the infected men were also less likely to have been circumcised -

circumcision can also prevent HIV infection - and may have engaged in

more risky behaviour. So did the vaccine actually do something, or

were the results a fluke?

" I don't think we really do know, " Dr. Gottesdiener of Merck

Research Laboratories told Reuters.

Nearly 30 potential AIDS vaccines are being tested in people around

the world.

" It is very important for the future of the field, " said Margaret

ston, director of the AIDS vaccine research program at the NIAID.

" It makes us rethink some of the candidates that are in trial, " said

Dr. Seth Berkley, president of the International AIDS Vaccine Initiative.

Even vaccine advocates are calling it a setback.

" These data are deeply disappointing and troubling, and raise more

questions than answers for the field of AIDS vaccine, " said AIDS

Vaccine Advocacy Coalition executive director Warren.

" This setback should not and can not diminish our commitment to

developing an effective HIV vaccine, " said NIAID director Dr.

Fauci. " Every day, another 12,000 people become infected with HIV,

most of whom live in resource-poor countries, " he added.

The researchers agree the finding could at the very least scare people

off from taking part in AIDS vaccine trials. And because HIV only

infects people, having human volunteers is key to finding a way to

prevent an infection that has killed 25 million people and affects 40

million more.

" That is why we are being completely transparent, as open as

possible, " Fauci said in a recent interview.

Berkley agreed. " I am only worried if there is a lot of buzz,

misinformation around, " he said.

But the fact that vaccine volunteers even became infected drives home

the need for a vaccine, said Berkley. All the volunteers were

counselled about ways to avoid HIV infection, and given condoms. " If

those behavioural change interventions worked, we wouldn't need a

vaccine, " Berkley said.

" People will get infected despite the best counselling possible. "

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