Poultry traders wait for customers at a market in Ha Tay province near Hanoi, Vietnam. The government earlier this week confirmed the first bird flu outbreak in the northern part of the country in more than a year.

Jakarta, Indonesia ? Building a global stockpile of vaccine to fight a pandemic would help ensure that poor countries do not lose out to wealthy nations if a flu virus starts killing people around the world, the World Health Organization said as it works to end a standoff with Indonesia over the issue.

Only up to 500 million doses of vaccine currently can be produced worldwide, far short of the amount needed to protect the world’s population in a major pandemic. Indonesia and other developing countries in Asia fear they would not have access to the limited supply of bird flu vaccine, even though they provided the viruses to make it.

A so-called virtual stockpile, in which countries would pledge to donate a portion of their vaccine, is one short-term strategy that could guarantee at least some vaccine would be equitably distributed within poor countries in the event of a pandemic, David Heymann, WHO’s top flu official, said Friday.

A long-term goal would be for poor nations to receive enough technology and training to produce vaccines themselves, he said.

“What we need to do and want to do is develop mechanisms that will permit countries to have access to vaccines if they need it,” Heymann said, adding that Brazil and India are involved in projects to produce vaccines with help from experts.

Indonesia was sharply criticized last month when it announced it would not send H5N1 bird flu virus samples to WHO unless the agency guarantees that the specimens will not be used commercially.

Under the system used for sharing seasonal flu viruses for the past 50 years, countries send specimens to WHO that are then made freely available to the global community for public health purposes, including vaccine development. Indonesia has not shared any viruses since the beginning of 2007.

Indonesian Health Minister Siti Fadilah Supari said the country had instead agreed to work with U.S. drug manufacturer Baxter Healthcare Corp. to make a bird flu vaccine. Under the agreement, Indonesia will provide H5N1 bird flu virus samples in exchange for Baxter’s expertise in vaccine production.

On Thursday, Supari said WHO Director-General Margaret Chan had promised by telephone that the country’s virus samples would not be made available to vaccine manufacturers for commercial use.

WHO has said that a letter is being formulated and will be sent to Supari outlining the organization’s position. Heymann would not comment on the letter, but said he hopes Indonesia will resume sending virus samples immediately.

A meeting with several countries is planned later this month in Jakarta to discuss vaccine development and virus sharing, along with proposals for improving the current system.

WHO closely monitors the H5N1 strains it receives to ensure the virus is not changing in a way that would allow it to spread easily among people.

Bird flu has killed at least 167 people since it began ravaging Asian poultry stocks in late 2003. It remains difficult for people to catch, and most human cases have been linked to contact with infected birds. Experts fear, however, that it could mutate into a form that sparks a pandemic, potentially killing millions.