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The World Health Organization urged drugmakers to reserve some of their pandemic swine flu vaccine for poor countries, but received few concrete offers as experts disclosed that an effective flu shot is still months away.

The global body wants companies to donate at least 10 percent of their production or offer reduced prices for poor countries that could otherwise be left without vaccines if there is a sudden surge in demand. But some are skeptical about what such a commitment could mean for their business.

"I don't think that all of the answers are there yet," said Swiss pharmaceutical giant Novartis AG spokesman Eric Althoff.

U.N. Secretary-General Ban Ki-moon, who met with 30 major pharmaceutical manufacturers, called Tuesday for global solidarity in confronting the disease. Solidarity "must mean that all have access to drugs and vaccines," he added.

The only major drugmaker that publicly agreed to the WHO request Tuesday was Britain's GlaxoSmithKline PLC, which said it would donate 50 million doses in a pandemic and offer more that WHO could buy at a discount for poor countries.

A second drugmaker with only limited production capacity said it would share half of its vaccine doses. WHO officials declined to identify the company because the deal has yet to be signed.

Smaller vaccine makers from developing countries also promised to share 10 percent of their vaccines with the U.N. at cheaper prices.

"I can reassure you I have received very serious commitments," WHO Director-General Dr. Margaret Chan told reporters after meeting with the drugmakers. Nearby, health ministers from around the world gathered for WHO's annual assembly and discussed how to tackle the outbreak.

Swine flu has been confirmed in more than 9,830 people in at least 40 countries, with most of the cases in Mexico and the U.S. That figure does not include Taiwan which reported its first confirmed case on Wednesday. The global death toll was at least 83 — 74 in Mexico, seven in the U.S., one in Canada and one in Costa Rica.

The impact of a pandemic — a global epidemic — is expected to be worse in poor countries, where people with other diseases such as AIDS and malaria are more susceptible to swine flu and national health systems are less able to respond.

Many rich countries — including Britain, Canada, Denmark, France and Switzerland — have already signed deals with vaccine makers that promise them millions of pandemic vaccines as soon as they're available.

Others companies that attended the Geneva meeting, including Sanofi-Aventis and Baxter International, could not immediately be reached for comment.

Manufacturers won't be able to start making the vaccine until mid-July at the earliest, weeks later than previous predictions, according to an expert panel convened by WHO. It will then take months to produce the vaccine in large quantities.

The swine flu virus is not growing very fast in laboratories, making it difficult for scientists to get the key ingredient they need for a vaccine, the "seed stock" from the virus, WHO said.

Experts also found no evidence that regular flu vaccines offer any protection against swine flu.

They estimated that under the best conditions, drug companies could produce nearly 5 billion doses of swine flu vaccine in the year after beginning full-scale production.

One expert, however, thought the 5 billion dose estimate was too optimistic.

"We should go forward with production as quickly as possible, but we should be cautious" about predictions, said David Fedson, a vaccine expert and former medical professor at the University of Virginia.

Chan has warned that it would be impossible to produce enough vaccine for all 6.8 billion people on the planet.

In any case, mass producing a pandemic vaccine would be a gamble, as it would take away manufacturing capacity for the seasonal flu vaccine that kills up to 500,000 people each year. Some experts have wondered whether the world really needs a vaccine for an illness that so far appears mild.

U.S. Health and Human Services Secretary Kathleen Sebelius said Tuesday the U.S. felt it had a responsibility to ensure that both antiviral drugs and any new vaccine are also available to poor countries. The United States has so far refrained from reserving any new vaccine.

Sebelius said the United States is working to boost its production capacity for seasonal flu vaccines so those factories could switch to the pandemic swine flu strain if needed.

"At this point we have not placed orders for vaccine," Sebelius told reporters in Geneva. "There is still so much uncertainty about this virus that it is really premature for us to even make a determination of how many people would appropriately be vaccinated, in what order, how many doses would be required."