The World Health Organization said on Tuesday it was up to national regulatory authorities to decide whether to extend the shelf life of the flu drug Tamiflu by two years, as recommended by Swiss drug maker Roche.

The United States, Canada, Australia, Hong Kong and the European Union's drug watchdog have extended Tamiflu's shelf life to 7 years from 5 after company data showed the active ingredient's longer stability, a Roche spokeswoman said.

Tamiflu, known generically as oseltamivir, is the frontline antiviral being used against the H1N1 virus, commonly known as swine flu, which is causing an influenza pandemic.

Capsules kept in government stockpiles worldwide or currently on the market carry a five-year expiry date.

It is WHO's view that shelf-life extensions are a matter for national regulatory authorities, WHO spokesman Gregory Hartl said in a statement sent to journalists.

The WHO says most people infected with H1N1 have mild symptoms and Tamiflu should be given only to flu sufferers at high risk including pregnant women or those with complications such as pneumonia.

The European Medicines Agency has said it is acceptable to apply the extension to current stocks of the drug during a flu pandemic, a decision followed last month by Switzerland.

We are working with health authorities to also extend the shelf life in other markets because it makes sense, Roche spokeswoman Claudia Schmitt told Reuters.

270 MILLION COURSES

Roche was providing its stability data to governments to help them extend the shelf life of their stockpiles, she said.

Governments have had stockpiles since the bird flu time, she added, referring to the H5N1 avian flu strain which erupted in 2003 and also responds to treatment with the antiviral.

Since 2004, Roche has filled government orders for 270 million Tamiflu treatment courses in 96 countries, Schmitt said.

The drug manufacturer has donated about 10.65 million treatment courses to the WHO for distribution and use in the poorest countries. The first donation to the U.N. agency was made in 2004 and the second in May as H1N1 spread more widely.

A large amount of the second donation is newly produced. It is a product that will expire many years from now, she said.

The WHO spokesman said the agency did not have any new estimate of global production capacity for vaccines now being developed by drug companies.

The WHO has previously estimated that drug companies could produce up to 94 million doses per week but the amount will depend on factors including whether one dose or two is needed, and how much of the active agent will be needed per dose.

In the United States, Novavax Inc reported on Tuesday a new kind of flu vaccine worked against the H1N1 virus in ferrets, the closest animal to humans when it comes to being infected with influenza. [nN18341687]

Leading flu vaccine makers include Sanofi-Aventis, GlaxoSmithKline, Novartis, Baxter, CSL and Solvay.

In Dar es Salaam, WTO Director-General Margaret Chan said work on producing a vaccine was proceeding, now that manufacturers in developed and developing countries had received the seed virus from the WHO's collaborating centers.

We expect vaccines, the first batch of which would be available in September, October, Chan told reporters.

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