Friday, May 18th, is ?World AIDS Vaccine Day.?  On this date, 10 years ago, former President Bill Clinton challenged the world to develop an AIDS vaccine within a decade. That hasn?t happened yet.

Dr. Pat Fast is senior director of medical affairs for IAVI, the International AIDS Vaccine Initiative. From New York, she spoke to VOA English to Africa Service reporter Joe De Capua about the search for an effective vaccine.

?We don?t have a vaccine yet that we know works. I think that a lot of progress has been made in terms of understanding basic science, finding out some things that don?t work, developing new approaches and developing a lot of capability to test vaccines internationally in ways that we didn?t have before,? she says.

Dr. Fast says that over the past ten years research has started in many more countries. ?There?s been a huge shift, I think, in where research is being done. The earliest AIDS vaccine research was done in the United States and Europe. And it took some time to involve the clinicians and scientists and people in countries that really are the most desperately in need of the HIV vaccines because they?re the hardest hit by the epidemic. Now, there?s much more proportionate, more reasonable proportion of the effort that?s going on in Africa and to some extent in Asia as well,? she says.

The IAVI official says there are numerous problems in finding an HIV vaccine. One is that the virus mutates and is able to escape the immune system response. Another is the difficulty in developing a strong and thorough anti-body response with a vaccine that would allow the immune system to destroy the AIDS virus.

Dr. Fast says funding for vaccine research has greatly increased. She says, ?There has been a lot of push by IAVI and by many other advocates to increase funding. And over the past 10 years, $186 million in 1997, $759 million in 2005.?