The World Health Organization's flu chief urged drug makers on Saturday to donate swine flu vaccines to the world's poorest countries, which are more vulnerable in the fight against the pandemic. Dr. Keiji Fukuda said the agency is working hard to lobby the world's rich nations and flu vaccine makers for donations. «It is clear that the poorest countries in general are just the most vulnerable to any number of diseases, and so it is a big concern,» Fukuda said on the sidelines of a symposium of health officials and experts in Beijing, according to a report of The Associated Press. «We're continually hoping that more of the companies will step up and agree to donate more of the vaccine.» WHO says the swine flu virus _ also known as H1N1 _ has killed almost 1,800 people worldwide as of Aug. 13.