Bird Flu Alarm

Understanding Avian Influenza

Race to Find a Vaccine to Guard Against Bird Flu

Aug. 28--Decades after it died out, Spanish flu still has the ability to send a shiver down the spine: The disease which swept the word in 1918 killed more people than the first world war.

Scientists have been warning that the next devastating global flu pandemic is due. And, right on time, a virus has arrived that could make their chilling predictions come true. That virus is bird flu.

Last week, farmers in the Netherlands were told to keep their poultry inside over fears that migrating birds would spread the lethal virus from Russia.

It is not only deadly to birds. The virus has jumped the species barrier; 112 cases have been reported in humans, causing 57 deaths.

Researchers are working to develop a vaccine to guard against the flu, caused by the H5N1 strain. But they are faced with scientific and logistical challenges to produce it in enough quantity to provide widespread protection.

A vaccine's efficacy cannot be known until bird flu strikes because volunteers are not exposed to the real deal; H5N1 mutates constantly, compounding the difficulty. And six times the normal dose appears to be required compared with protection from seasonal flu, putting great pressure on production. The production process itself is delicate, requiring careful cultivation in chickens' eggs. H5N1 flu production is likely to prove even more difficult, given that the strain involved is lethal in chickens. Cell-based cultures could be used instead.

Once a vaccine is approved, mass production would take a minimum of three months and more likely six months. The disease itself may not be understood for another two years, experts say. The UK is also tendering for a contract to supply 2m doses of a H5N1 vaccine once one is available.

Earlier this month, the US National Institute of Allergy and Infectious Diseases unit, offered grounds for optimism when it announced successful results of a vaccine developed by Sanofi-Pasteur. It suggested the vaccine might be able to protect healthy adults against the H5N1 flu strain. Findings are still due from tests to see whether it will work in the elderly and children.

GlaxoSmithKline (GSK) is gearing up to file for preliminary European regulatory approval for a pandemic flu vaccine that could be used to tackle the future spread of the lethal H5N1 virus. The move, likely by the end of the year, marks an early attempt by one of the world's largest vaccine manufacturers to prepare for high-volume production.

The company has already run clinical trials showing successful treatment of other flu strains using its vaccines in combination with a common "adjuvant" -- additives that substantially boost the human immune response and which are already used in some other types of vaccine.

While medicines cannot kill viruses outright, drugs exist that can limit the impact by slowing down their spread. This principle works with the current HIV/Aids treatments called antiretrovirals, which are capable of stabilising a patient's condition over many years.

GSK's antiviral flu medicine Relenza and Roche's rival drug Tamiflu are two such medicines. They can attack enzymes in flu viruses to hinder their ability to multiply in the body.

Antivirals like these have a role in helping to stem the spread of what could become one of the most troubling worldwide public health threats of the coming years, while effective vaccines are developed.

Understanding Avian Influenza