David Heymann, assistant director-general for communicable diseases at the WHO, said bird flu virus samples are tradable goods and must be treated as such by drug companies and industrialized countries.
"We must figure the right way to move ahead to make sure that sharing of these public goods -- the viruses -- also leads to sharing of the benefits," said Heymann during a panel discussion about pandemic diseases at the Pacific Health Summit in Seattle. "We have to take this to heart very clearly."
The WHO, a United Nations agency, is under pressure from developing countries hard-hit by bird flu to try to devise a new formula for sharing of samples and the resulting benefits.
Indonesia, which has the world's highest number of fatalities from bird flu, this year refused to share samples of the H5N1 avian influenza virus with the WHO unless it had guarantees that they would not be used commercially.
A five-month hiatus ended in March when the two sides reached an agreement to improve access to safe and effective H5N1 vaccines and other potential pandemic influenza vaccines.
Indonesian Health Minister Siti Fadillah Supari has said that it will require drug companies wishing to develop a vaccine from its samples to seek its permission. In exchange, Jakarta would seek guarantees on preferential priding, fair distribution of vaccines worldwide and transfer of technology.
Some health and aid agencies had criticized Indonesia for refusing to share samples, while others defended the stance because developing countries often struggle to get access to life-saving drugs due to patent laws and high costs.
According to the World Health Organization, H5N1 flu has infected 312 people in 12 countries --Nigeria, Thailand, Vietnam, Indonesia, China, Turkey, Azerbaijan, Iraq, Egypt, Djibouti, Laos and Cambodia -- and killed 190 of them.
Although it remains mainly an animal disease, scientists fear that if it mutates into a disease easily spread amongst people, it could kill millions.
Drug manufacturers in at least 10 countries are working on vaccines against H5N1, but only a few thousand doses are available. They are based on current H5N1 strains and no one knows how well the vaccines will match a future pandemic strain.
Influenza vaccines have to be reformulated every year to match the circulating strains because the virus mutates.