BERLIN — The ninth international meeting on AIDS ended here Friday after 5,500 presentations that showed little more than incremental gains in scientific knowledge about the disease.
"Our progress seems desperately slow," Dr. Michael H. Merson, the director of the World Health Organization's AIDS program, said at the close of the weeklong meeting. His remarks to the more than 14,000 participants also reflected gloom about the spread of HIV, the virus that causes AIDS, in many areas of the world.
"With regard to science, it's best to be frank," Merson said. "We cannot report the big breakthroughs on preventive vaccines for which the world is waiting."
He added that "there have been disappointments" in drug treatment aimed at the virus. "We must accept that our scientific advances today are coming in small steps, not in leaps and bounds," Merson said.
Nevertheless, Dr. Lars O. Kallings, a Swedish epidemiologist, said the meeting offered abundant new information about vaccines, the dynamics of the spread of the various genetic subtypes of HIV and the way the virus damages the immune system.
Experimental vaccines made by genetic engineering techniques are showing evidence of high levels of immune responses that are lasting longer in human volunteers than researchers had expected, said Dr. Dani Bolognesi of Duke University.
In a meeting at the WHO's headquarters in Geneva last week, experts urged intensive exploration of vaccines made from weakened live virus instead of those made by genetic engineering techniques.
Most scientists have feared developing such attenuated vaccines for AIDS because the virus in the vaccine, though weakened, could still mutate and cause disease.
But faced with a relentless epidemic, attitudes began to change after a report from scientists at the New England Regional Primate Center in Southborough, Mass., who made an attenuated vaccine by removing a gene from the simian AIDS virus, which is related to the human AIDS virus and inflicts a disease that closely parallels AIDS in humans. The resulting vaccine offered the strongest protection to date.