Booster vaccination may help with possible future avian influenza pandemicJuly 17, 2008New evidence suggests that a booster vaccination against H5N1 avian influenza given years after initial vaccination with a different strain may prove useful in controlling a potential future pandemic. The study is published in the August 1 issue of The Journal of Infectious Diseases, now available online. H5N1 continues to pose a major health risk to birds and humans. As of mid-June, more than 60 percent of the more than 380 human cases have been fatal, and hundreds of millions of birds have died or been culled to prevent the spread of the disease. Should the virus evolve making human-to-human transmission more likely, a destructive global influenza pandemic could result. The cornerstone of planning for such a possible pandemic is the development and distribution of effective vaccines. Several vaccines have been developed, but as the virus continues to mutate into genetically distinct lineages, or clades, the problem arises as to whether vaccines based on an older clade will be effective against newer versions. The new study is the first to report that giving one dose of a newer-clade vaccine to those who were vaccinated previously with older versions is more effective than giving only doses of the newer vaccine to unvaccinated subjects.
The study, conducted by Nega Ali Goji, MD, and colleagues from New York, Maryland, and Alabama, gave a single booster dose of a vaccine based on a clade 1 H5N1 virus circulating in Vietnam in 2004 to subjects who eight years earlier had received two doses of a vaccine based on the original, clade 0 virus that appeared in Hong Kong in 1997. Sixty-four percent had a positive immune response, which compares favorably to the results of a previous study using two doses of the clade 1 Vietnam virus, in which only 43 percent of those vaccinated had a positive immune response. The results not only support the booster technique, but also show that even though the virus had mutated since the initial vaccination, using it to boost an earlier vaccine is more effective than simply vaccinating subjects with the most current vaccine. These findings are important given the fact that influenza viruses are mutating constantly. "These results suggest that one strategy for pandemic control could involve prevaccination of some segments of the population prior to the emergence of a pandemic so that effective protection could be achieved with a single dose schedule if and when a pandemic emerges," the authors wrote. "If the finding that priming can result in enhanced responses to single-dose vaccination schedules were confirmed, then pre-pandemic vaccination programs could be considered, especially in populations of first responders, health care workers, or the military. Such populations might then be able to be effectively and rapidly vaccinated with a single dose of a vaccine specific for an emerging pandemic if it were to occur." In an accompanying editorial, Gregory A. Poland, MD, of the Mayo Clinic College of Medicine, noted that some are already looking to begin such prevaccination primers against H5N1 influenza. For example, Japan is planning to immunize health care workers starting in 2009, and the U.S. Department of Defense is offering a vaccine to those in high risk specialties. Dr. Poland pointed out that new studies are needed to investigate different types of vaccine administration, deal with vaccinations that prevent death but not infection and illness, search for more broadly cross-protective influenza vaccines, and collect data on the vaccination of those who are not healthy adults. Although, he said, "determining who should receive these vaccines, when, and in what order and under what circumstances deserves widespread debate," he agrees that the findings of the study are novel, as they "suggest that such a prime-boost strategy using vaccines derived from different H5 clades, separated by years, may be worthwhile, immunologically feasible, and safe." Infectious Diseases Society of America | |||||||||||||||||||||
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Related Avian Influenza Current Events and Avian Influenza News Articles 'Deadly dozen' reports diseases worsened by climate change Health experts from the Wildlife Conservation Society today released a report that lists 12 pathogens that could spread into new regions as a result of climate change, with potential impacts to both human and wildlife health and global economies. Scientists working to protect NI from Bird Flu Queen's scientists are involved in two international projects aimed to protect Northern Ireland's agri-food industry from Bird Flu and African Swine Fever, a disease which kills pigs. Discovery opens door for drugs to fight bird flu, other influenza epidemics Researchers at Rutgers University and The University of Texas at Austin have reported a discovery that could help scientists develop drugs to fight the much-feared bird flu and other virulent strains of influenza. The pandemic potential of H9N2 avian influenza viruses Since their introduction into land-based birds in 1988, H9N2 avian influenza A viruses have caused multiple human infections and become endemic in domestic poultry in Eurasia. Newly described 'dragon' protein could be key to bird flu cure Scientists and researchers have taken a big step closer to a cure for the most common strain of avian influenza, or "bird flu," the potential pandemic that has claimed more than 200 lives and infected nearly 400 people in 14 countries since it was identified in 2003. Battling bird flu by the numbers A pair of Los Alamos National Laboratory researchers have developed a mathematical tool that could help health experts and crisis managers determine in real time whether an emerging infectious disease such as avian influenza H5N1 is poised to spread globally. New Clorox disinfectant is EPA registered to kill both known types of MRSA While MRSA has been an issue in healthcare settings for years, CA-MRSA outbreaks in the community have been on the rise, with the greatest risk in community settings such as fitness clubs, in sports teams, at schools and daycare centers. New strategies against bird flu The Spanish flu outbreak of 1918 killed between 30 and 50 million people. In the infected patients, the ultimate cause of death was acute respiratory distress syndrome (ARDS). New vaccine may give long-term defense against deadly bird flu and its variant forms A new vaccine under development may provide protection against highly pathogenic bird flu and its evolving forms, according to researchers at Purdue University and the Centers for Disease Control and Prevention who discovered the new preventative drug and have tested it in mice. Scientists create first successful libraries of avian flu virus antibodies An international group of American and Turkish research scientists, led by Sea Lane Biotechnologies, has created the first comprehensive monoclonal antibody libraries against avian influenza (H5N1) using samples from survivors of the 2005/2006 "bird flu" outbreak in Turkey. More Avian Influenza Current Events and Avian Influenza News Articles |
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