The news about bird flu is getting scarier every day. Rightnow it?s confined to Asia, but like SARS, it will travel towhere you are soon. Researchers now think there are definitecases of one person passing it to another, meaning it couldcause an epidemic that will rival the flu pandemic of 1918.Scientists are concerned that it will take too long to manufacture enoughdoses of a bird flu vaccine for a wide vaccination program,so a vaccine may notbe able to prevent a pandemic.
Instead of waiting for a pandemic strain to show up, healthauthorities in many different countries are creating humanvaccines against the current strain. These vaccines aren’tperfect, but drug manufacturers hope they’ll make thedifference between life and death. The sooner new bird fluvaccines are tested, the sooner vaccine makers can startmaking the vast quantities that will be needed throughoutthe world.
The main ingredient in any flu vaccine is the viral proteinhaemagglutinin, or HA. Vaccines against ordinary flu contain15 micrograms each of three varieties of HA. Drug companieshave decided to make the bird flu vaccine as similar toordinary flu vaccines as possible, to ease approval by theFDA. The problem is that studies show that people who havenot been exposed to HAs before do not receive an immunizingeffect from even large doses of them. Japan, Canada andAustralia plan to offset this by adding chemicals to thevaccine that are known to boost the immune system. This alsomeans that each dose of the vaccine will need to containless HA, which is important, because production of HAs islimited.
It would take six months to produce 180 million dosescontaining 15 micrograms of HA, and past studies have shownthat people need two shots, three weeks apart, to developimmunity to new flu strains, so that is enough serum tovaccinate only 90 million people. If all the vaccine plantsworldwide were working overtime, they still could produceonly enough serum for 450 million people.
The 2004 outbreak of bird flu in Vietnam finally stoppedafter they killed millions of infected poultry. But the flureturned December, probably because the virus was found inducks that showed no symptoms from it. Since December, 22people have tested positive for bird flu in Vietnam, and 14people have died from it. Five of these cases occurred in away that suggests the virus passed from person to person,instead of from poultry to people, as it always has before.
One way to determine if the bird flu virus can be spreadfrom person to person will be to watch out for the samething that happened with SARS: doctors, nurses and otherhealth care workers will begin to get the disease.
Like SARS, you can sometimes we unaware that you have birdflu. Antibodies against the disease were found in the81-year-old grandfather of a brother and sister who got birdflu, meaning he was infected but survived, despite hisadvanced age. The healthy wife of a 69-year-old man who diedfrom bird flu in February has also been found to have theantibodies inside her. This suggests that many infectionsare undetected, which means that the virus may not be aslethal as it first appeared, when three-quarters of patientswith confirmed cases of bird flu died. But if many morepeople are harboring bird flu than we’ve realized, it alsomeans that there is a greater chance they’ll pass it on toother people.
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