Bird flu kills three people in Vietnam
Deaths swing spotlight back to vaccine efforts.
A strain of bird flu has taken three lives in Vietnam, health authorities revealed yesterday, renewing fears of a human pandemic and focusing attention on the sluggish progress towards a vaccine.
The deaths, which were announced by Vietnamese health officials on 12 August, are the first to be reported since February this year, when avian influenza swept through poultry in Asia. At present, a second wave of disease is hitting flocks, mainly in Thailand and Vietnam.
Like those earlier in the year, the deaths have kindled fears of a human pandemic. This could be sparked if a human flu strain meets and mixes with the bird flu in a person's body, creating a hybrid virus that can jump between people and to which we lack natural immunity. So far, there is no sign that the bird flu has acquired such an ability.
Before 2004, doctors had seen only a handful of human cases of bird flu. But in January and February, a strain called H5N1 erupted among bird flocks in Asia, eventually killing 23 people. At that time, two laboratories, one in the United States and one in Britain, used H5N1 to create a modified, harmless strain for an experimental vaccine.
After intensive culling and vaccination, some countries announced that they had rid flocks of the disease. But many experts predicted it would bubble up again. In July, new infections in poultry were reported in several countries including Thailand, Vietnam, China and Indonesia. A different strain of bird flu thought to be less dangerous to humans was reported in South Africa earlier this month.
Experts are unsure whether the new infections arose because the disease lay low in a few poultry stocks, remaining undetected or unreported, or whether poultry became re-infected from the wild birds that are thought to harbour the disease.
Either way, this re-emergence suggests that the virus is likely to crop up again and again, says bird flu expert Richard Webby at St. Jude Children's Research Hospital in Memphis, Tennessee. "We've got to face the situation that it might be here to stay," he says.
The strain of flu behind this week's deaths has been identified as an H5 strain, the World Health Organization (WHO) said yesterday. It is not yet known whether this is exactly the same H5N1 strain which caused the spate of human fatalities earlier in the year.
St. Jude Children's Research Hospital in Memphis, Tennessee.
Thompson says the new deaths highlight concerns about how quickly a prototype vaccine is being pursued. Fears about the pandemic waned when human cases stopped appearing and Thompson says, "The pace has slowed."
But Linda Lambert, who directs vaccine research at the US National Institute of Allergy and Infectious Diseases, says that she and her colleagues are working flat out to produce a prototype jab. In May, the institute awarded contracts to Aventis Pasteur and Chiron Corporation to manufacture 8,000 to 10,000 doses of a vaccine each.
The doses should be delivered in the autumn, says Lambert, after which small clinical trials will start to establish safety and suitable dose. But even if production of the vaccine could start tomorrow, it would take several months at least to mass-produce millions of shots.