Abstract
This report summarizes U.S. influenza activity from September 28, 2008, the start of the 2008-09 influenza season, through April 4, 2009, and reports on the 2009-10 influenza vaccine strain selection. Low levels of influenza activity were reported from October through early January. Activity increased from mid-January and peaked in mid-February. Influenza A (H1N1) viruses have predominated overall this season, but influenza B viruses have been isolated more frequently than influenza A viruses since mid-March. Widespread oseltamivir resistance was detected among circulating influenza A (H1N1) viruses and a high level of adamantane resistance was identified among influenza A (H3N2) viruses.
MeSH terms
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Adolescent
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Adult
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Antigens, Viral
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Child
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Child, Preschool
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Drug Resistance, Viral
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Hospitalization / statistics & numerical data
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Humans
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Infant
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Influenza A Virus, H1N1 Subtype* / drug effects
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Influenza A Virus, H1N1 Subtype* / isolation & purification
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Influenza A Virus, H3N2 Subtype* / drug effects
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Influenza A Virus, H3N2 Subtype* / isolation & purification
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Influenza A virus / isolation & purification
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Influenza B virus* / drug effects
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Influenza B virus* / isolation & purification
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Influenza Vaccines
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Influenza, Human / drug therapy
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Influenza, Human / epidemiology*
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Pneumonia / mortality
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Population Surveillance*
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United States / epidemiology
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Young Adult
Substances
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Antigens, Viral
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Influenza Vaccines