The first swine flu patient to show resistance to the anti-viral drug Tamiflu has been identified in Denmark.
The virus has not previously shown resistance to Tamiflu, made by Roche, or GlaxoSmithKline's Relenza. Both antiviral medicines have been successful in reducing the severity of the disease when administered in the first few days.
Roche said the patient, who has since recovered on his own, had received a low dose of the drug and that it expected some people to show resistance.
"This one case of a resistant virus doesn't change our recommendations to use Tamiflu," the Danish National Board of Health said in the statement
The World Health Organization reported today 70,893 cases of the virus globally today. More than 300 people have died worldwide.
Meanwhile a nine-year-old girl with underlying health problems has died in Birmingham after contracting the virus.
A NHS West Midlands spokeswoman said: "We can sadly confirm that a child died at Birmingham Children's Hospital on Friday evening.
"The child has since tested positive for swine flu but had other serious underlying health conditions."
Dr Vivienne Nathanson, head of science and ethics at the BMA, said: "The fact is that any kind of flu can kill people of any age.
"Flu can kill even completely healthy people if they get pneumonia but, if they have got other health problems, they are more likely to get complications."
She said the British Health Protection Agency (HPA) was watching closely to work out the rate and type of complications from swine flu.
Dr Nathanson said experts were being "very, very fastidious" at chasing down cases and recording data that was being used to inform the response to the pandemic.