A New HIV Vaccine Shows Promise-but It Won't Be a Silver Bullet

Published: September 5, 2013

 Researchers at Western University in Ontario, Canada, announced today that a newly developed HIV vaccine passed the first phase of clinical trials. That’s extremely good news, of course, but it should still be approached with a healthy dose of caution. The announcement doesn’t mean that scientists have discovered an effective vaccine against HIV—and even if they had, such a tool would be far from a silver bullet in the fight against AIDS.

If Western University’s vaccine actually works, it will, without a doubt, change the face of HIV prevention. A vaccine for the virus has been famously elusive; every trial thus far has failed, some disappointingly, some disastrously. The most effective trial produced a vaccine that’s just 31 percent effective, a figure low enough to make further trials impracticable. The worst, without a doubt, ended just last April, when doctors discovered that their vaccine might increase patients’ risk of contracting the disease.
So a vaccine whose effectiveness matched even, say, that of a flu shot (about 60 percent) would be a big deal. But the effectiveness of Western University’s vaccine remains a giant question mark, as researchers took the relatively unorthodox route of testing their shot on already-infected patients. The trial produced encouraging preliminary results: HIV-positive patients began producing exponentially more antibodies to attack HIV-related antigens. In other words, the vaccine kick-started patients’ immune systems, provoking them to fight back against a virus they would normally succumb to. And it did so without producing any adverse effects. That’s certainly auspicious. But it doesn’t necessarily follow that the vaccine will be as effective in preventing HIV-negative people from acquiring the virus. That question will be tested in the trial’s next phases.
In the meantime, it’s best to remain wary of purported HIV cure-alls. Every few months, doctors and scientists announce a purported cure for HIV: flooding newborns with antiretrovirals, say, or transplanting bone marrow. As a rule, these remedies are limited or one-off—not everyone has the luxury of a bone-marrow transplant, after all—but researchers can’t resist extrapolating upon their implications for the broader population. (How often are we told there will be a cure within months?)
That’s an understandable impulse, given how discouraging the field of HIV research can otherwise be. But trumpeting such announcements and speculating about their sweeping implications often distracts from more concrete and practical developments in the field. To wit: There is already a vaccine more effective than the flu shot at preventing HIV. It’s called circumcision. Research suggests circumcision reduces the risk of HIV acquisition by 60 to 70 percent over the course of one’s lifetime (if you’re straight, at least)—unlike a condom, which must be used properly during every sexual encounter. And while HIV-prevention circumcision drives are catching on in Africa, the circumcision rate in the United States is dropping dramatically. (This phenomenon is due in part to angry, though discredited, “intactivists.”)
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