By ALICE PARK Monday, Jan. 25, 2010
Dr. David Ho was sitting in the audience during an AIDS meeting in 2007 when the presenter flashed a cartoon onscreen to make a point. Along with his colleagues, Ho chuckled at the image of a blindfolded baseball player swinging mightily at an incoming pitch. But as amused as the scientists were, they were sobered too; they knew that the player in the cartoon was them. A swing and a miss, the image was saying, one of many in the long battle against AIDS.
Ho certainly got the message. For nearly a quarter of a century, he and other AIDS scientists had been whiffing repeatedly, failing to make contact as HIV stymied them again and again. Powerful drugs to foil HIV could do only so much. To corral the epidemic and truly prevent HIV, only a vaccine would do. The problem was that no vaccine strategy had ever succeeded in blocking the virus from infecting new hosts, and that wasn't likely to change in the near future. "It struck a special chord with me," says Ho of the baseball image. "I think it accurately pictured our chance of success. We all felt that frustration."
Since that meeting, much has changed, but the fundamental problem of developing an effective AIDS vaccine remains. On the positive side, in 2009, scientists announced that they had developed the first vaccine to show any effect against HIV infection — although that effect is, by all measures, modest. The vaccine's ability to reduce the risk of new HIV infection 31% is nowhere near the 70% to 90% that public-health experts normally view as a minimum threshold for an infectious-disease vaccine. Even further behind in development, but still promising, are two new antibodies identified by a group of researchers working at a number of labs that, at least in a dish, seem to neutralize the virus and thwart attempts to infect healthy cells.
The excitement over those advances, however, has been tempered by the still raw memories of a humbling retreat in 2007, after a highly anticipated shot against the virus was deemed a failure. While nobody expected spectacular results, neither did anyone expect such a stunning defeat, and the scientific community is still struggling to recover from it. "We are still a long ways away from having an effective HIV vaccine that physicians can reach into the cabinet and pull out in a vial and inject into a person," says Dr. Bruce Walker, an HIV expert at Harvard Medical School.
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