The problem with any antiviral drug is that the virus can develop resistance to it. Doctors are concerned that the flu could become resistant to Tamiflu, just as the influenza A strain has become resistant to the antiviral drugs Symmetrel (amantadine) and Flumadine (rimantadine).
Some flu strains have already shown resistance to Tamiflu, including those found in a few patients with the avian flu. Health officials are concerned that during a pandemic, when infection persists for a longer period, the risk for resistance could be even higher.
In 2005, Roche donated 3 million treatment courses (30 million capsules) of Tamiflu to the World Health Organization to create an international stockpile. The company donated an additional 2 million courses (20 million capsules) to the WHO in January 2006.
Because Roche is the sole patent owner, the company has had a difficult time producing enough to go around. This is partially due to the difficulty in isolating shikimic acid from star anise in large quantities. Roche continues to increase its manufacturing capability. It claims that by 2007, it will be able to produce over 300 million treatments of Tamiflu annually, more than ten times the production in 2004.
Some countries said they would ignore the patent and manufacture generic versions of the drug, while others said they would license their own version from Roche to protect people in the event of a pandemic. In 2005, Roche granted Vietnam permission to produce a generic version of the drug. That same year, the Indian drug company Cipla announced that it would defy Roche's patent and make its own generic version of the drug without a license. Recently, Roche granted sublicenses to manufacture Tamiflu to a Chinese and an Indian drug company [ref].
With fears rising about a potential bird flu pandemic, it's not surprising that many Americans are thinking about keeping their own supply of the antiviral drug. But is it a good idea? Many health experts warn against the practice, saying that it's often difficult to know whether you have the flu or just a garden-variety cold, and taking Tamiflu too often could lead to the development of drug-resistant virus strains. The World Health Organization has recommended that governments stockpile antiviral medications in advance of a pandemic to ensure that sufficient supplies are available.
To learn more about Tamiflu, the flu and bird flu, check out the links in the next section.