December 16, 2001
It is clear that a vaccine to help reeducate the immune system to control HIV is needed. The antivirals we use have short and long-term side effects that make it clear that for some, just treating HIV with these medications will not have a truly successful outcome given these toxicities.
However, there are few examples of any therapeutic vaccination being successful, so it is clear this search will not be an easy one. In fact, after several years of studies on therapeutic vaccination, the benefits observed to date have been modest at best, leading to some indication of an impact on CD4 decline at most. What is clear now is that we have a better understanding of the cells we need to stimulate with a vaccine and hopefully this can translate into a more effective vaccine itself.
The research so far suggests that recreating both CD4 "helper" cells and CD8 cytotoxic cells are key to helping control HIV replication. Why don't they currently work well enough for most people? There are several possible reasons for this but it remains unclear what the essential defect is. However, it now appears that those who have a history of a low CD4 count (below 200 cells) are much less likely to respond to vaccine-type strategies even after their counts rebound on antivirals.
Dr. Lederman concluded that there are many challenges to this field. There are no or few precedents of success to build from. There is as yet no test to use to see if a vaccine has been successful. There is also no clear way to know if the vaccine strain of HIV used will help control someone's individual HIV -- which may differ.
But he points out that, ironically, since the primary problem of HIV is one of immune deficiency, there is some hope that correcting this deficiency with a vaccine may one day allow a person to actually control HIV.
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