By Deborah Mitchell

ANNECY (Reuters Health) - When AIDS (news - web sites) first came to light about 20 years ago, it was at the bottom of the "Richter scale" of global diseases--and now it has risen to the top, Dr. Robin Weiss of University College London told participants at the opening session of the 13th Cent Gardes Symposium on HIV (news - web sites) and AIDS Vaccines here Sunday evening.

Weiss noted that AIDS is now expanding worldwide more rapidly than hepatitis B and C viruses, measles and influenza.

"In another 20 years, we don't know what will be at the top," Weiss continued. "Let us hope that it won't be HIV and that we shall have safe and efficacious vaccines." However, this will certainly be a "big challenge."

The sense of urgency for a safe and effective vaccine was echoed by other opening speakers. To date, 60 million have been infected with HIV worldwide and one third of these individuals have died, Dr. Wayne Koff of the International AIDS Vaccine Initiative (IAVI) told the audience. Life expectancy has been reduced by half in many sub-Saharan African countries, and "shows no signs of letting up." And the pandemic is spreading rapidly through parts of Asia.

"At the present time, we still haven't got a candidate in the clinic that is inducing effective neutralizing antibodies against HIV," Koff said.

As IAVI first announced in Barcelona at the International AIDS Conference in July, the nonprofit initiative has formed a consortium with the NIH's vaccine research center in the US and a number of other academic institutions to make the single issue of neutralizing antibodies a priority in the search for a vaccine.

"We believe this is a solvable problem," Koff said.

IAVI is also willing to commit substantial resources to the problem of engineering and manufacturing a vaccine once it is developed. This is just as important as the scientific issues, Koff said. "It would be unconscionable if we identify a vaccine that is safe and effective in the clinical trials and then are not able to make this vaccine available as fast as possible."

In addition, IAVI is continuing research in monkeys to help answer some questions posed at the first Cent Gardes meeting that still remain unanswered today, he said. "What are the antigens that we need; what are the immune responses that we have to induce; and what is the best vaccine approach to have protection against AIDS?"

He concluded on a note stressing the urgent need for progress. "HIV is still out there--it's changing--and every day of this meeting another 15,000 people will become HIV-infected."