Updated

With swine flu now an official pandemic, the race is on among drugmakers to produce a vaccine.

GlaxoSmithKline said Thursday after the World Health Organization declared a global flu epidemic that it would be ready within weeks to begin large-scale vaccine production. Sanofi-Aventis also said it had started working on its own version. On Friday, Swiss pharma giant Novartis announced it had created an experimental vaccine that has been tested in people. Novartis' vaccine was made via a cell-based technology that may prove faster than the traditional way of making vaccines, which relies on chicken eggs.

Many rich countries like Britain, Canada and France signed contracts with pharmaceuticals long ago, guaranteeing them access to pandemic vaccine. WHO and others estimate that about 2.4 billion doses of pandemic vaccine could be available in about a year.

The likely scramble for vaccines will leave many people in poorer countries empty-handed.

So far, swine flu has been mostly detected in developed countries like the United States, Europe, Japan and Australia.

"We do not know how this virus will behave under conditions typically found in the developing world," WHO chief Dr. Margaret Chan said Thursday. She said the agency expects to see a "bleaker" picture as the virus makes its way to Africa and Asia. About 85 percent of the world's chronic diseases are found in poorer countries. More than 60 percent of the world's HIV cases are also in Africa.

WHO spokesman Gregory Hartl said officials were concerned people in poorer countries and those fighting other health problems like malaria, tuberculosis, malnutrition and pneumonia might be more susceptible to swine flu.

On Friday, WHO said that 74 countries had reported nearly 30,000 cases including 145 deaths. But so far, the virus appears to be mild. Most people don't need medical treatment to get better.

But the virus might have a more devastating effect in people with underlying health problems. About half of the people who have died from swine flu have had complications like asthma, diabetes, and obesity.

"Any population that has health challenges is potentially going to be at higher risk with H1N1 (swine flu)," Hartl said.

In May, officials led by Chan and U.N. Secretary General Ban Ki-moon asked vaccine makers to save a portion of their production for poor countries. Chan said she was aiming to get 10 percent of the global pandemic vaccine supply reserved for poor nations.

Only one large company, GlaxoSmithKline PLC, agreed to help. The drug giant offered to donate 50 million doses of pandemic vaccine to WHO for distribution to developing countries. Several smaller firms also made offers, but their production capacity is limited.

Because more than 95 percent of flu vaccines are still made in eggs, the Novartis announcement is unlikely to significantly boost the world's pandemic vaccine supply.

WHO and nongovernment organizations like Oxfam are continuing to ask drugmakers to make some of their pandemic vaccines available for poorer countries at a cheaper price, as well as asking donor countries and organizations to pay for the doses.

But in a pandemic situation, WHO's attempts to secure vaccine for the poor and even the contracts countries have signed with drugmakers may make little difference to who actually gets the vaccine, some experts say.

In previous pandemics, vaccines have never left the country where they are made before all of that country's own needs have been met.

"WHO can say whatever it wishes, but pharmaceutical companies will take their marching orders from the politicians," said David Fedson, a vaccines expert and former professor of medicine at the University of Virginia.

"Do you think any doses of vaccine made in France, Germany, the Czech Republic or anywhere will be allowed out to go to other countries just because there's a contract?" Fedson said.

Ultimately, Fedson said health officials and politicians will have to deal with a limited amount of vaccine for the billions worldwide who want it. "There's a lot of dirtiness in vaccine politics," he said. "We may try our best, but we won't succeed in doing what's necessary."