Australia, Hong Kong report Tamiflu-resistant flu

GENEVA (Reuters) - Australia and Hong Kong have joined North America and parts of Europe in reporting seasonal influenza viruses with increased resistance to the antiviral drug Tamiflu, the World Health Organization said on Thursday.

The WHO said that it was still gathering global data about "an increased number of (seasonal) H1N1 viruses with resistance to oseltamivir" following the first reports which emerged in Europe in late January.

Oseltamivir is the generic name for Tamiflu, made by Switzerland's Roche Holding AG and Gilead Sciences Inc of the United States, which governments worldwide have been stockpiling as a first line of defense in case the bird flu virus sparks a human influenza pandemic.

The mutated H1N1 showing resistance is a sub-type of ordinary influenza A, different from the H5N1 virus which causes bird flu. But the resistance to Tamiflu has raised questions about its potential effectiveness in a deadly bird flu pandemic.

Spokeswoman Sari Setiogi said that for now the WHO was not changing its recommendation that Tamiflu be used to treat seasonal flu.

"We still expect to see more testing be done," she said.

In Hong Kong, 5 of 67 samples of the H1N1 virus tested, or 7 percent, showed resistance to Tamiflu, according to a WHO table. In Australia the rate was 2 out of 36 samples, or 6 percent.

In Japan, where Tamiflu is widely prescribed for seasonal flu, none of the 71 samples tested showed resistance, WHO said.

A week ago, the WHO reported that the main seasonal virus circulating in both Canada and the United States showed "elevated resistance" to Tamiflu. These rates are 6 percent and 8 percent, respectively, according to the WHO's latest figures.