November 19, 2012
Toronto's The Star reported November 9 that a Phase I HIV vaccine trial conducted by Ontario's Western University had found signs of boosted immune response to HIV with no vaccine-related adverse effects. Phase I trials evaluate safety and efficacy with a small number of trial participants. "Researchers were expecting a two or threefold increase in the level of HIV-1 antibodies," The Star reported, "but were pleasantly surprised when one individual showed a 32-fold increase, and another a 10-fold increase."
The SAV001-H vaccine being evaluated is unusual in using whole HIV virus, genetically altered to be non-pathogenic and further inactivated with chemicals and radiation. Most other developmental vaccines use viral fragments too small to replicate.
Phase I trials come very early in the FDA approval process, so FDA approval of the vaccine -- if ever -- is years away. If the vaccine shows a high percentage of protection in later field trials, though, it may revolutionize the campaign to end the epidemic. We don't need a vaccine to be 100% effective. We just need it to be effective enough that the number of further infections from each new infection in a broadly vaccinated population -- so-called rho -- falls below one. Once rho is less than one, the natural momentum of the epidemic is to shrink.
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