Medical reports presented at the conference and several other recent studies offered both hope and frustration. The news:
Microbicides: Researchers from UNAIDS discovered to their horror that the spermicide nonoxynol-9, a chemical found in many contraceptive lubricants and gels worldwide, is not only ineffective against HIV, it actually appears to increase the chance of infection in high-risk women. Of 999 prostitutes in Africa and Thailand, 59 women using a nonoxynol-9 contraceptive gel called Advantage-S became infected with HIV, compared with 41 women using a placebo. HIV infections are rising most rapidly among women, and while condoms are good protection, many men–especially in Africa–won’t use them. Researchers have been working hard to find an effective microbicide (a chemical that can kill off the virus) and were hoping that nonoxynol-9 was the answer. The quest will continue: three dozen microbicides are now in the preclinical testing stage, and 20 others are ready for safety trials in humans.
Intermittent therapy: Protease inhibitors have improved the health and extended the lives of many patients–but they’re expensive, must be taken on a strict regimen and can have debilitating side effects. Scientists have wondered: can patients safely take a break from the drugs? It’s still far too early to tell, but Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, reported on two ongoing clinical trials that show some promise. In one, nine patients took medication for two months, then stopped for one. Their virus levels increased when medication was halted, but dropped back to undetectable levels once the drugs were restarted. In the second study, therapy was interrupted every other week: virus levels rose without medication, but only minimally. One of the biggest unknowns is whether intermittent therapy will induce dangerous drug-resistant forms of the virus. Researchers warned that until they know more, patients should never take drug holidays without clinical supervision.
Vaccines: The International Aids Vaccine Initiative announced that small human trials would soon begin on the first vaccine developed specifically to fight the A-strain of HIV, the most common type in much of Africa. The new vaccine was designed to mimic the immune response of a small group of Kenyan prostitutes who have remained uninfected despite repeated exposure to the virus. So far, more than 25 HIV vaccines have been tested, but only one, AIDSVAX (designed to fight subtypes B and E), has made it to large-scale clinical trials, now ongoing in the United States and Thailand. One of the greatest obstacles is HIV’s spectacular ability to mutate into different subtypes. But even a partially effective vaccine–still years away–would be a welcome weapon against a pandemic that has killed nearly 19 million people already.
