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March 23, 2006

Health Officials May Vaccinate Before a Human Pandemic BeginsA Primary Health Care Weekly


March 20 (Bloomberg) -- Health officials are considering vaccinating people in high-risk countries even before avian flu becomes contagious among humans.

Keiji Fukuda, head of the World Health Organization's global influenza program in Geneva, said for the first time that health officials are weighing whether to use vaccines created to combat the current H5N1 strain before an outbreak occurs, an aggressive tactic that some suspect may help slow the growth of a pandemic that many say is inevitable.

``Can we begin vaccinating rural populations against an avian influenza where it is a problem now?'' he asked in a wide- ranging interview at the International Conference on Emerging Infectious Diseases in Atlanta. ``It's one of the things that has to be talked through.''

Fukuda wants to explore whether current vaccines, such as those made by Sanofi-Aventis SA and Chiron Corp., can be given safely since they're still undergoing testing, and health officials have limited experience with them. The vaccines are created using killed viruses that have proteins on their surfaces like those on the germ circulating in birds.

Fukuda didn't say who would fund such a vaccination program that focuses on poor people in undeveloped countries. The U.S. government paid Sanofi and Chiron to develop shots that can be stockpiled for use in case the strain of flu spreading in birds mutates into a human disease.

Fukuda's comments come the same day the U.S. government released a study showing that the bird flu virus spreading around the world is mutating into more variations with genetic characteristics that increase the risk of infection in humans.

Variant Virus

Researchers are finding more human cases of the disease caused by a variant that had only been seen in birds before 2005, said Rebecca Garten, a U.S. Centers for Disease Control and Prevention scientist who led the study. The research was presented today at the same conference where Fukuda spoke with a Bloomberg reporter.

More surveillance is needed to track new forms of the virus that may acquire the ability to spread from person-to-person, Garten said. Government officials said earlier this month that federal laboratories are developing a second bird flu vaccine to provide more protection against new strains.

``As the virus continues its geographic expansion, it is also undergoing genetic diversity expansion,'' Garten said in an e-mailed statement before the conference. ``Change is the only constant.''

Data Sharing

Fukuda, who became head of the WHO flu effort this year, also said in the interview that he and his colleagues at the WHO are also pushing for greater sharing of data on the virus and more virus testing sites in poor nations. The organization is currently seeking sites in Africa to fit laboratories for bird flu testing, Fukuda said.

The H5N1 bird virus has spread from Asia to Africa, the Middle East and Europe, and has recently shown increased ability to infect mammals, such as cats, according to the U.S. Centers for Disease Control and Prevention Web site. The disease has infected 177 people, mostly though close contact with birds, and killed 98 of them, according to the WHO Web site.

Health officials are preparing for the chance that it will mutate into a lethal form that might spread quickly around the world, like the Spanish flu of 1918 that killed at least 50 million people worldwide, 500,000 of them in the U.S.

Six-Month Gap

Experts believe it will take at least six months to develop a vaccine against a pandemic strain of influenza after it mutates into a form contagious to people. A worldwide disease outbreak would probably also cut off international travel and interfere with vaccine distribution in remote areas and poorer countries, Fukuda said.

``When I look at the current possibility for vaccination in the face of a pandemic, it doesn't look very good to me,'' Fukuda said.

Sanofi and Chiron's vaccines are still undergoing testing to see if they can be safely boosted with chemicals called adjuvants so that smaller doses will protect more people, said Nancy Cox, chief of the CDC's influenza branch.

The vaccine might be most appropriate for people at the highest risk of infection, such as health workers or those culling poultry, she said.

``It's very wise to debate and discuss how to use this vaccine that's already been produced,'' she said in an interview. ``Certainly this vaccine has the potential to provide some level of protection to those who might be at the front lines.''

Bird Testing

Fearing that the U.S. may be hit with the particularly lethal bird flu in the coming months, the departments of the Interior and Agriculture said March 8 they would ramp up testing for bird flu beginning in April. About 100,000 migratory birds are expected to be tested this year, compared with an average of about 12,000 in years past.

Testing will be concentrated in Alaska and Hawaii, said Chuck Higgins, director of the National Park Service's office of public health, on March 16. Millions of birds nest in Alaska each year, coming from Asia and North America, he said.

The genetic type of H5N1 that began infecting humans last year is called genotype Z, clade 2 and contains numerous variations that have been seen in humans, the study researchers said. In 2003 and 2004, clade 1 viruses were responsible for most

To contact the reporter on this story:
John Lauerman in Boston at  jlauerman@bloomberg.net.
Last Updated: March 20, 2006 15:53 EST

Posted by dymaxion at March 23, 2006 11:51 PM

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