President Bush has called on bird flu vaccine makers to step up production (the vaccine is injected into birds). The White House has brought the bird flu pandemic threat issue higher up On its agenda as concerns of a global threat increase.

Bush met with heads of pharmaceutical companies and urged them to do all they can.

Representatives from 80 countries at the United Nationals met in an attempt to lay down a global plan of action against a bird flu pandemic.

Mike Leavitt, US Health and Human Services Secretary admitted that American vaccine production in general is below what it should be. He said vaccine production improvements are needed.

It is crucial, said one US official, for countries to share information as it appears - immediately. There is concern that some nations may drag their feet or cover things up, as did China three years ago during the SARS outbreak. If this were to happen as a bird flu pandemic erupted, the consequences could be devastating for the whole globe.

A UN official earlier this week said a flu pandemic could kill over 100 million people.

The geographical spread of bird flu is widening with Romania reporting its first cases - three dead ducks found in the Danube came up positive for avian influenza. Officials do not yet know whether it is the H5N1 strain - the most dangerous one.

The present bird flu, especially the H5N1 strain, could mutate so that humans could infect humans - this is the great worry. Currently, humans can only become infected from birds. The virus does have a limited capacity to pass from human to human, but contact with an infected person has to be constant - as was the case with some health professionals who got infected caring for infected patients. However, those infected health professionals did not then go on to infect other humans outside the hospital.

Scientists believe the Spanish Flu Pandemic, which took place in 1918, was a bird flu virus that mutated. 50 million people are thought to have perished during that pandemic.

The world population is much bigger than it was in 1918, people travel much more. If the virus mutated and managed to jump from human to human it would probably make its way around the world at lightning speed and infect and kill many more people than the 1918 one did.

Over 60 people have died from the current bird flu - all of them in South East Asia. The only drug that offers some help to patients is called Tamiflu, an antiviral prescription drug. However, there are reports of virus resistance to this drug.