Roche says some seasonal flu resistance to Tamiflu

GENEVA - Swiss pharmaceutical company Roche said on Wednesday that its anti-viral treatment Tamiflu was effective in treating swine flu.

But it acknowledged that cases of drug resistance had emerged with seasonal flu last winter.

"There was resistance against a seasonal strain of H1N1, where Tamiflu was not effective for a certain number of people," a Roche spokeswoman said.

However, the World Health Organisation had "confirmed that Tamiflu is effective against the current swine flu," she added.

Potential mutations of the virus needed to be watched especially during the winter season which was beginning in the southern hemisphere, the Roche spokeswoman said.

On Wednesday, WHO expert Nikki Shindo said the development of a vaccine against influenza A(H1N1) was partly triggered by "widespread evidence of oseltamivir resistance in seasonal influenza" last year.

"So given that we have winter in Southern American countries and also the other parts of the southern hemisphere, there will be a risk of having viruses that will be highly resistant to antivirals," Shindo said.

Flu outbreaks are at their most active during winter.

Oseltamivir is the active ingredient in Tamiflu, an anti-viral which is stockpiled by many national governments against influenza and a possible pandemic.

Roche said on Tuesday it was donating 5.65 million treatment courses of the drug to the WHO to help fight the swine flu outbreak and boosted its production capacity for the next five months.

In the absence of an efficient vaccine against influenza A(H1N1) for now, only Tamiflu and Relenza, made by GlaxoSmithKline, are considered efficient treatments for those who fall ill.