Drug-resistant H1N1 no major change in virus, WHO says

GENEVA — Tamiflu resistance in some H1N1 patients with badly weakened immune systems does not seem to reflect a major change in the virus' susceptibility to the frontline drug, the World Health Organization said Nov. 26.

Nine people in Britain and the United States developed a Tamiflu-resistant form of H1N1 flu while being treated in hospital mainly for blood cancers, said WHO flu expert Keiji Fukuda.

"We don't know the full answer. But it is more likely that we are not seeing a change, a major shift in the epidemiology or in the properties of these viruses with regard to oseltamivir resistance," he told a weekly news conference.

He said Tamiflu, known generically as oseltamivir and made by Switzerland's Roche, was effective when used correctly and early.

About 75 cases of oseltamivir-resistant viruses have been reported worldwide in recent months, mostly isolated cases that have arisen after preventive treatment with the drug, he said.

"Right now we do not see any evidence of a large impact in immuno-compromised people with milder forms and we do not see a large impact in HIV-infected populations."