Why researchers think folks over age 65 may not catch H1N1 novel flu
It's still all theory, but UC Davis researchers think that the reason senior citizens over age 65 aren't catching the H1N1 flu at least for now is that specific shared molecular sites called epitopes result in some type of immunity to the novel flu. It seems people over age 65 have been exposed to various type A flu viruses in the past that have stimulate immunity responses in which their T-cells clear out the novel flu viruses.
What are epitopes? They also are called determinants on the surface of the antigen. Scientists use the term to describe the peptide fragments at T cells recognize. It's your T cells that fight any foreign object such as a virus that comes into your circulatory system.
What the UC researchers did was to look at data from older studies of previous swine flu epidemics. The scientists identified the molecular sites, that is the epitopes where strains of H1N1 virus found in California, New York, and Texas share with the regular seasonal type A flu viruses.
Senior citizens, it's theorized, might share those molecular sites or epitopes which gives them some type of immunity to the novel H1N1 strain (the new swine flu). It's a fascinating theory because some doctors have been heard to say partially in jest that nothing moves faster than seasonal flu through a senior citizen's nursing home. So what might cause adults older than age 65 to possibly be more resistant to the H1N1 novel flu virus?
Last month, a 53-year old nurse with no underlying diseases died of swine flu. You've read of cases where 55-year olds contracted swine flu. What makes the difference between a 55 and a 65 year old? Could it be exposure to the flu pandemics in 1957 and 1976?
You could theorize your own ideas. Could older adults be more immune because in 1976 so many were vaccinated with a specific strain of swine flu protection? But what about the millions not vaccinated?
Another question for scientists to explore might be, whether even though H1N1 is a different strain, could it still have provided some protection for adults that also survived or had immunity to the 1957 worldwide flu pandemic when these people were teenagers or young adults?
Or what about the flu outbreaks in February 1966 and December 1970 or 1972? Flu outbreaks usually seem more severe every two years. What causes the cycle or make the first week in January and the entire month of Februrary the peaks of seasonal flu season?
Interestingly, the new research is being performed by two UC Veterinary Medicine scientists to validate theories that at least so far people 65 and older could have natural protection from the swine flu, even though season flu is known to sweep through nursing homes. To find out more information, check out the coming November 2009 issue of the scientific journal, Emerging Infectious Diseases, published by the Centers for Disease Control and Prevention.
You can read further information on this UC Davis research in an article about the research of the two UC Davis scientists named in the Sacramento Bee in today's article. See the article, "UC Davis pair confirm findings on seniors' immunity to swine flu," by Anita Creamer. Wed October 14, 2009. Also see the Centers for Disease Control updates on H1N1 flu virus. For further information, also see the H1N1 press updates from the CDC, "CDC H1N1 Flu | Press Updates."
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