Bird flu vaccine could take months, U.N. says

Drug firms could take six months to manufacture adequate stocks of bird flu vaccine, far too long to stem damaging fallout if the virus triggers a human pandemic, a top United Nations official said on Tuesday.

David Nabarro, U.N. coordinator for global readiness against an outbreak, said current stockpiling by governments around the world might prove useless since they are preparing for an unknown mutation of the virus.

He said "very high priority" efforts were underway to raise manufacturing capacity so that a vaccine could be produced more quickly once a virus with pandemic potential manifested itself.

"We do not know what the genetic makeup of the eventual mutant virus will be, therefore we cannot be sure that existing vaccines that have been stored up will be effective," he said.

"The general view in a pandemic situation is that we need to have vaccines much more quickly than six months because of the speed at which the pandemic can take hold and start to affect the functioning of society and cause suffering."

Avian influenza (also known as bird flu) is a type of influenza virulent in birds. It was first identified in Italy in the early 1900s and is now known to exist worldwide.

The causative agent is the avian influenza (AI) virus. AI viruses all belong to the influenza virus A genus of the Orthomyxoviridae family and are negative-stranded, segmented RNA viruses.

Avian influenza spreads in the air and in manure. Wild fowl often act as resistant carriers, spreading it to more susceptible domestic stocks. It can also be transmitted by contaminated feed, water, equipment and clothing; however, there is no evidence that the virus can survive in well cooked meat.

The H5N1 bird flu virus has killed at least 65 people in four Asian nations since late 2003, and has killed or forced the destruction of tens of millions of poultry.

Experts say it is mutating steadily and fear it will eventually acquire the changes it needs to spread easily from person to person. If it did, it could sweep around the world in months or even weeks and could kill millions of people.

Asked by reporters if vaccine stockpiling was futile, Nabarro said: "I would not identify any preparatory activity being taken by governments at the moment as wasteful.

Avian influenza in humans
Of the 15 subtypes known, only subtypes H5, H7 and H9 are known to be capable of crossing the species barrier from birds to humans. It is feared that if the avian influenza virus undergoes antigenic shift with a human influenza virus, the new subtype created could be both highly contagious and highly lethal in humans. Such a subtype could cause a global influenza pandemic, similar to the Spanish Flu that killed over 20 million people in 1918 (though a variety of sources quote average figures even higher, up to 100 million in some cases). Many health experts are concerned that a virus that mutates to the point where it can cross the species barrier (i.e. from birds to humans) will inevitably mutate to the point where it can be transmitted from human to human. It is at that point that a pandemic becomes likely."What we're talking about here is very difficult choices being made by governments in a situation of uncertainty."