The U.S. National Institutes of Health has cancelled
a study testing an experimental HIV vaccine because scientists concluded it did
not prevent infection or reduce the amount of HIV in the blood. HIV is the
virus that causes AIDS.
The so-called HVTN 505 study began in 2009 and is
one of several such studies underway to find an effective AIDS vaccine. The
study involved over 2,500 volunteers, specifically men who have sex with men
and transgender people who have sex with men.
"This trial has provided a clear, swift answer
about a specific vaccine strategy. It's not the answer we hoped for, but the
search doesn't end here," Mitchell Warren, executive director of the
nonprofit group AVAC: Global Advocacy for HIV Prevention, said in a statement.
While the failure of the vaccine is a blow to HIV
vaccine research, the National Institutes of Allergy and Infectious Disease
said it would continue to monitor the volunteers.
The experimental vaccine in the cancelled trials was
based on a common cold virus. It was used to introduce HIV genes into the body
to prime the immune system to provide a vaccine boost.
Matthew Rose, a participant HVTN 505 study, remained
hopeful that an HIV vaccine will eventually be developed.
"These results do not change the fundamental
view that an AIDS vaccine remains critical to any long-term strategy to end the
AIDS epidemic," Rose told Reuters.
There are two traditional methods for creating a
vaccine. One uses a weakened or attenuated version of a live virus to generate
an immune response. The other uses a dead virus.
Both methods are proven to be safe and effective,
except when it comes to HIV. Vaccine candidates produced by these methods
simply have not been successful in people when it comes to the AIDS virus.
A Thai study from 2009 still has many hopeful. But
even that study involving a vaccine known as RV 144 was judged to provide only
31 percent protection against HIV.
Sources :
http://www.voanews.com/content/hiv-vaccine-study-cancelled/1649820.html
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