Experts Warn of Killer Flu; China Says it Has New Bird Vaccine

By Patrick Goodenough | July 7, 2008 | 8:16 PM EDT

( - Amid fresh warnings by scientists that Asia's avian flu virus could trigger a human pandemic threatening millions of lives, Chinese researchers say they have developed a new vaccine capable of stopping the strain's spread in birds and poultry.

Experts are seriously concerned that unless the virus known as H5N1 is wiped out in birds, it could change into a form that moves between humans, with catastrophic results.

The Xinhua news agency quoted the head of the China National Bird Flu Reference Laboratory, Chen Hualan, as saying two new vaccines for birds developed by her laboratory had an efficiency rate of "100 percent."

Chen said the lab had received Ministry of Agriculture permission to market the vaccines and that poultry farms in Vietnam, a bird flu hotspot, had begun experimenting with them.

Avian flu vaccines already are being widely used on birds in Asia, where almost 100 people have been infected since 2003. More than 50 of them have died from the virus since 2003 in Vietnam, Thailand and Cambodia.

China recently reported its first bird flu case since last year. The virus was present in migrating wild geese, found dead in a nature reserve, prompting concerns that it could spread to a large population of domestic poultry.

Beijing was criticized widely in 2003 for its slow and secretive response to an outbreak of severe acute respiratory syndrome (SARS), a disease that originated in China and spread to almost 30 other countries, killing some 800 people.

This time, it moved quickly to tell the public to avoid nature reserves, and ordered that millions of birds in the affected region be vaccinated.

Nonetheless, a spokeswoman for the World Health Organization (WHO) office in Beijing said Friday it was still waiting for authorities to provide more information about the geese.

"We've asked for further information on whether any humans might have been exposed to these birds, where the birds might have come from. We'd also like to get samples of the virus so we can determine if it's the same as that which is circulating in Vietnam, or slightly different."

Hans Wagner of the Food and Agriculture Organization - another U.N. agency monitoring the outbreak - said from Thailand Friday the office was still waiting for information from the Chinese on the new and reportedly more effective vaccine.

One of the risks of vaccinating birds is that the vaccine can allow H5N1 to persist covertly, by suppressing symptoms but not removing the cause.

Because of this, Wagner said, "additional measures" were required, such as putting non-vaccinated birds into vaccinated flocks, to establish whether the virus was still circulating undetected.

"It's not an easy process. It's also a costly process."

'Millions at risk'

Flu experts gathered in Manila recently concluded that H5N1 strains circulating in Vietnam were "possibly becoming more infectious for people."

WHO's regional office said that there was no conclusive evidence, yet, of human-to-human transmission.

Scientists are, however, lining up to warn that governments are not prepared for the possibility that the virus could mutate into an easily-transmitted form and kill millions of people.

The publication Nature devoted a special edition this week to concerns about a flu pandemic, with experts warning on the huge human and economic impact it could have.

"Unless the international community now moves decisively to mitigate this pandemic threat, we will in all probability pay heavily within a few years," Nature said in an editorial. "Then, hard questions will be asked as to why we were not prepared."

It urged better coordinated, better funded efforts by governments and international agencies, both to develop sufficient vaccine to cope with demands during a pandemic and to meet "the first priority ... to prevent a pandemic emerging in the first place, by extinguishing the disease in animals."

On Thursday, Centers for Disease Control and Prevention director Julie Gerberding told lawmakers that 15 to 35 percent of the U.S. population would be affected by a medium-level flu pandemic, which she said would cost the country's economy between $71.3 billion and $166.5 billion.

Also testifying before a House health subcommittee, Dr. Andrew Pavia of the Infectious Diseases Society of America said the United States was "woefully unprepared."

He called for a "rational, integrated, and comprehensive plan" to ensure the U.S. has sufficient doses of vaccine as well as antiviral drugs, which can slow the rate of infection.

Experts note that in 1968, 750,000-800,000 people died during a pandemic of a "relatively mild" avian flu virus. In 1918, the "Spanish Flu" (H1N1) pandemic killed an estimated 20-40 million people worldwide.

See earlier story:
Bird Flu Poses Global Threat, Health Officials Warn (Feb. 24, 2005)

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Patrick Goodenough
Patrick Goodenough
Spencer Journalism Fellow