New strains of the flu virus are showing resistance to drugs that experts had hoped would slow the spread of any pandemic, research suggests.
Tamiflu is viewed as the best weapon currently available against a flu pandemic, and is being stockpiled by governments including the UK’s.
But Japanese researchers found evidence of emerging resistance to Tamiflu, and a second drug Relenza.
The study is published in the Journal of the American Medical Association.
Experts have warned that a flu pandemic could claim millions of lives around the world.
There is concern that the H5N1 strain of the virus – known as bird flu – could mutate to gain the ability to spread easily from person to person.
At present the virus, a type of the A strain of flu, does not have this ability, although it has killed 170 people since 2003. These were mainly poultry workers, who came into very close contact with infected birds.
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