Latest HIV vaccine doesn't work; govt halts study

Latest HIV vaccine doesn't work; govt halts study



WASHINGTON (AP) — The latest bad news in the
hunt for an AIDS vaccine: The government halted a large U.S. study on
Thursday, saying the experimental shots aren’t preventing HIV infection.




Nor did the shots reduce the amount of the
AIDS virus in the blood when people who'd been vaccinated later became
infected, the National Institutes of Health said.




‘‘It’s disappointing,’’ said Dr. Anthony
Fauci, head of NIH’s National Institute of Allergy and Infectious
Diseases. But, ‘‘there was important information gained from this’’
study that will help determine what to try next.




The study had enrolled 2,504 volunteers,
mostly gay men, in 19 cities since 2009. Half received dummy shots, and
half received a two-part experimental vaccine developed by the NIH. All
were provided free condoms and given extensive counseling about the
risks for HIV.




It’s a strategy known as ‘‘prime-boost.’’ A
DNA-based vaccine made with genetically engineered HIV material is given
to prime the immune system to attack the AIDS virus. Then a different
vaccine, encasing the same material inside a shell made of a disabled
cold virus, acts as a booster shot to strengthen that response. Neither
vaccine could cause HIV.




The idea: Train immune cells known as T cells
to spot and attack the very earliest HIV-infected cells in someone’s
body. The hope was that the vaccine could either prevent HIV infection,
or help those infected anyway to fight it.




A safety review this week found that slightly
more study participants who had received the vaccine later became
infected with HIV. It’s not clear why. But the difference wasn’t
statistically significant, meaning it may be due to chance. Overall,
there were 41 HIV infections in the vaccinated group and 30 among
placebo recipients. When researchers examined only participants
diagnosed after being in the study for at least 28 weeks — long enough
for the shots to have done their job — there were 27 HIV infections
among the vaccinated and 21 among the placebo recipients.




The NIH said Thursday that it is stopping
vaccinations in the study, known as HVTN 505, but that researchers will
continue to study the volunteers’ health.




Josh Robbins, 30, of Nashville, Tenn., is
among the participants who became infected. He said he’s glad he was in
the study, because its close monitoring meant he was diagnosed and
treated much sooner than most people — and he’s feeling great — and
because the findings help science.




‘‘We've got to keep moving forward,’’ Robbins
said. The study ‘‘certainly can lead us down a new direction to
hopefully find something that might work.’’




Multiple attempts at creating an AIDS vaccine
have failed over the years. A 2009 study in Thailand is the only one
ever to show a modest success, using a somewhat different prime-boost
approach. Newer research suggests another approach — to try creating
powerful antibodies that could work a step earlier than the T-cell
attack, before HIV gets inside the first cell.




Both approaches need continued research funding, said Mitchell Warren of the international AIDS Vaccine Advocacy Coalition.




‘‘Clearly an AIDS vaccine remains critical,’’ he said.

Source:-
http://www.boston.com/lifestyle/health/2013/04/25/latest-hiv-vaccine-doesn-work-govt-halts-study/RzN4b6h2VOPUAlDvYUZETP/story.html