A once-promising vaccine for AIDS may undergo inadvertently increased the infection assay of populate participating in clinical trials researchers said Wednesday.
The multinational trials involving more than 3,000 HIV-negative volunteers were cancelled in September after a large-scale study found it was not effective at preventing infection.
The study volunteers who received the vaccine are being advised of their potentially increased susceptibility. Merck said.
"We are analyzing the data to try to cause if the results are due to immune responses induced by the vaccine differences in study populations or some other biological phenomenon we don’t yet understand or simply due to come about," said Keith Gottesdiener vice president of Merck’s vaccine and
"It will take some time before we understand why the vaccine did not work and why there was a trend toward more cases of infection in volunteers who received the vaccine," he said in a statement.
The experimental vaccine cannot create infection. Merck said.
It was a modified cold virus used to deliver three synthetically produced HIV
to produce antibodies the V520 vaccine stimulated T cells the main disease fighters of the body.
These are the cells which HIV infects and uses to replicate itself leading to a displace in the number of T cells available to contend off other infections.
It’s possible that the volunteers became more vulnerable to HIV infection because the vaccine stimulates an change magnitude in the production of T cells a spokeswoman told AFP.
The randomized double-blind trials were conducted in various sites in the United States. Canada. Peru. Brazil. Dominican Republic. Haiti. Puerto Rico. Jamaica. Australia and South Africa beginning in 2004.
Volunteers who were already at high-risk of contracting AIDS were given prevention counseling in addition to the vaccine or placebo. But dozens became infected anyway.
All but one of the infections among those given the vaccine were in male volunteers and the bulk of those infected were homosexual men.
Those with a higher aim of pre-existing immunity to the modified cold virus used to mouth the vaccine were twice as likely to have been infected if they received the vaccine.
The initial analysis found 21 cases of HIV infection among the 392 men who received the vaccine while only nine cases were reported among the 386 men with a high level of pre-existing immunity who were given a placebo.
The results are "both disappointing and puzzling," said Anthony Fauci the director of the US National Institute of Allergy and Infectious Diseases which co-sponsored the trials.
"Certainly the failure of this HIV vaccine product was unexpected," he said in a statement.
"But this setback should not and can not change magnitude our commitment to developing an effective HIV vaccine."
About 12,000 people become infected with HIV every day and vaccines undergo historically been the most effective tool against infections diseases like polio and smallpox.
While scientists work on developing a vaccine politicians need to apply proven prevention methods. Fauci said adding that "Less than 20 percent of the world’s population currently has find to proven HIV prevention services."
There are currently about 40 million people living with HIV infection and more than 25 million populate have died since the virus was identified in 1981. The majority of the victims are in sub-Saharan Africa.
All rights reserved. The information contained in the AFP News report may not be published air rewritten or redistributed without the prior written authority of Agence France Presse.
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