Originating in Asia in 2003, birds infected with H5N1 have recently been discovered in Romania and Turkey. Scientists have been warning since 1997 that the rogue influenza strain known as H5N1 could be the one that triggers a pandemic rivaling the devastating Spanish flu of 1918 — which killed 50 million, by some estimates. Currently confined to transmission from birds, primarily poultry, to humans, it is reckoned that only about a dozen mutations are required for H5N1 to be able to spread between humans, and those mutations might arise even while remaining resident within the avian population, without more widespread transmission from animals to humans.

Tamiflu was invented in a San Francisco Bay Area lab. It is partly derived from a spice used in Chinese cookery.

Laboratory tests indicate that Tamiflu, and a lesser-known inhaled antiviral, Relenza, made by GlaxoSmithKline, are the only medications that can treat infection from H5N1.

The patent for Tamiflu is owned by Swiss pharmaceuticals giant Roche, which acquired rights to the drug from Gilead Sciences Inc. in 1996. Spokesman Terry Hurley said, “Roche ... fully intends to remain the sole manufacturer of Tamiflu.” Roche will not release its Tamiflu production figures, deeming it “commercially sensitive” information.

The immediate problem is not the cost of Tamiflu, which runs about $60 for a 10-pill course of treatment, but the sudden gap between the demand for it and the capacity of its sole manufacturer to manufacture it.

There is a growing uproar for Roche to allow other companies to manufacture the drug. During the 2001 anthrax scare, a similar outcry over patent rights occurred over Bayer Corp.’s antibiotic Cipro, though the threat to forced patent licensing never materialized.

"The WHO [World Health Organization] should buy stockpiles from generic suppliers," said James Love, director of the Consumer Project on Technology in Washington D.C. "If patents are in the way, the WHO should ask the manufacturing country to issue the appropriate compulsory licenses. The patent owner will receive royalties, but we will have the stockpiles." U.N. Secretary-General Kofi Annan concurred in remarks last week at WHO headquarters in Geneva.

In Bombay, Dr. Yusuf K. Hamied, chairman of Cipla Ltd., said that his company has already developed a generic version of Tamiflu, but the company cannot manufacture the drug owing to patent restrictions.