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Avian Flu Info: Looks like GSK, ROG.VK/GILD have the best vaccines so far:

FACTBOX-Bird flu's tendency to mistakes makes it dangerous
Fri Oct 14, 2005 05:27 PM ET
Oct 14 (Reuters) - A feared strain of avian influenza known as H5N1 has spread to birds in Turkey and is likely to continue moving, experts say.
The World Health Organization believes it is only a matter of time before the virus develops the ability to pass easily from human to human, possibly causing a catastrophic pandemic.

It is the virus's tendency to make mistakes when replicating itself that makes it so dangerous and unpredictable. Here are some facts about H5N1 avian influenza:

-- The H5N1 strain first emerged in Hong Kong in 1997, causing the death or destruction of 1.5 million birds and sickening 18 people, killing six.

-- It re-emerged in 2003 in South Korea, and has now spread to China, Vietnam, Thailand, possibly Laos, Indonesia, Turkey and perhaps Romania. Japan, Malaysia and South Korea are considered free of H5N1 avian flu after having outbreaks. H5N1 has also been seen in wild birds in Mongolia, Kazakhstan and Russia's Siberia.

-- The outbreaks have led to the death or destruction of an estimated 150 million birds.

-- H5N1 has infected 117 people in four countries and killed 60, according to the World Health Organization. Experts say more people may have been infected but were not ill enough to seek medical attention, so it is not known what the fatality rate is.

-- Avian flu exists almost everywhere. There are 15 subtypes of influenza virus known to infect birds, but the so-called highly pathogenic forms tend to be caused by influenza A viruses of subtypes H5 and H7.

-- Influenza type A viruses are named according to two proteins they carry call hemagglutinin (H) and neuraminidase (N). There are 16 possible "H" variations and nine "N."

-- Influenza viruses are RNA viruses, meaning they lack mechanisms for proofreading and repairing genetic errors. This makes them especially prone to mutation. This is why there is a new strain of seasonal flu almost every year and why the annual vaccine must be reformulated every year.

-- Some years this means the flu is not especially deadly but it usually kills 250,000 people at a minimum globally, in an average season. About every 20 years or so the virus changes enough to cause a pandemic that infects and kills many more people than usual.

-- Three pandemics occurred in the 20th century -- the 1918 pandemic that killed anywhere between 20 million and 100 million people globally, the 1957 "Spanish influenza" which killed an estimated 2 million people globally and the 1968 "swine flu" which killed 1 million. Experts agree another pandemic could occur at any time.

-- The seasonal flu vaccine provides no protection against H5N1 avian flu. There is an experimental H5N1 avian flu vaccine but there are only a few thousand doses and it is unlikely to provide perfect protection.

-- H5N1 mutates rapidly and is beginning to show some of the changes that made the 1918 H1N1 flu pandemic so deadly.

-- Four drugs work against influenza. But two older drugs, amantadine and rimantadine, already have minimal activity against H5N1. Two newer drugs work better. Tamiflu, known generically as oseltamivir, was invented by Gilead Sciences (GILD.O: Quote, Profile, Research) and is made and marketed by Swiss drug giant Roche Holdings (ROG.VX: Quote, Profile, Research) . Relenza, known generically as zanamivir, was developed by Australia's Biota Holdings (BTA.AX: Quote, Profile, Research) and is marketed by GlaxoSmithKline (GSK.L: Quote, Profile, Research) .

Relenza is a powder given via the nose and is considered less desirable than a pill like Tamiflu.

-- Just as bacteria develop resistance to antibiotics, viruses develop resistance to antivirals and H5N1 has become resistant to amantadine. It has also begun to show signs of mutating into a form resistant to Tamiflu.

-- Tamiflu and Relenza, in a class known as neuraminidase inhibitors, do not cure influenza infection but can reduce the severity of illness if given within 48 hours after symptoms begin. They may also help prevent infection if given early.

-- WHO has urged countries to develop preparedness plans, but only around 40 have done so. WHO predicts that most developing countries will have no access to vaccines or antiviral drugs throughout the duration of a pandemic, and experts say developed nations will not have enough to cope well.