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| health > story page |         |
New flu vaccine could provide longer protection
September 27, 1999
By Laura Lane (WebMD) -- A new vaccine could provide long-lasting protection from the flu, researchers reported this month in Nature Medicine. Because the flu virus mutates each year, health officials must develop new vaccines for every season. But a new vaccine targets a key protein in the influenza A virus that apparently never changes, says Walter Fiers, a professor at the University of Ghent in Belgium, who led a study of the vaccine in mice. The study was done in conjunction with researchers at the Flanders Interuniversity Institute for Biotechnology, also in Belgium.
New vaccines would still be necessary each year for protection from influenza B, the researchers say. The innovation is still important because, while influenza B is also common, influenza A causes the most devastating outbreaks. Influenza B also changes less from year to year, so people have more natural immunity to it. Currently, the typical flu vaccine immunizes against two strains of the influenza A virus and one strain of influenza B. Because the molecular composition of two key proteins differs from strain to strain, the flu vaccines must be changed every year, according to which strains are circulating. In influenza A, the two proteins have been known to undergo a significant change in their molecular structure, resulting in pandemics -- diseases that occur over a large area and affect a high percentage of people. In this century alone, such flu outbreaks have killed more than 20 million people worldwide, according to the Centers for Disease Control and Prevention. One pandemic was responsible for 500,000 deaths in the United States from 1918 to 1919. The new vaccine is based on a viral protein, known as M2, that is the same in most influenza A strains and doesn't change from year to year. Thus, the vaccine protects people from most strains of influenza A, Fiers says. A third virus, influenza C, does not cause symptoms severe enough to require vaccination. Fiers cautions that the vaccine does not protect against influenza B and has only been tried in mice so far. Of 12 mice vaccinated in Fiers' study, 11 survived symptoms caused by the influenza A virus, which researchers injected into the mice. Only two of 11 mice that weren't vaccinated survived. New York Medical College researcher Dr. Edwin Kilbourne, who wrote a commentary to accompany the new study, says the researchers shouldn't claim that the new vaccine is effective against multiple influenza A strains until the mice have survived exposure to several strains of the virus. In the study, researchers exposed the mice to two similar viruses. "It's in the right direction, but a lot more work has to be done before we talk about 'universal' anything," says Kilbourne, who has studied influenza viruses for almost 50 years. And by using milder flu symptoms, the researchers would have been able to define more clearly how the vaccine would work in humans, says infectious disease researcher Dr. Matthew Leibowitz of the University of California, Los Angeles School of Medicine. But the only way to have a "black and white answer," says Fiers, was to give the mice lethal doses of the virus. And the flu does kill people. About 20,000 people die from influenza-related complications every year, according to the CDC. Older people and those with chronic health problems are most at risk for developing complications, including pneumonia. Symptoms include fever, cough, sore throat, runny or stuffy nose, headache, muscle aches and extreme fatigue. Copyright 1999 by WebMD, Inc. All rights reserved. RELATEDS AT  :
Influenza RELATED STORIES: Cold and Flu Report RELATED SITES: Centers for Disease Control and Prevention
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