Estimating Seasonal Influenza-Associated Deaths in the United States: CDC Study Confirm... - 0 views
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CDC estimates that from the 1976-1977 season to the 2006-2007 flu season, flu-associated deaths ranged from a low of about 3,000 to a high of about 49,000 people. Death certificate data and weekly influenza virus surveillance information was used to estimate how many flu-related deaths occurred among people whose underlying cause of death was listed as respiratory or circulatory disease on their death certificate.
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deaths varies from year to year because flu seasons are unpredictable and often fluctuate in length and severity.
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the study confirmed previous findings that about 90% of influenza associated deaths occur among adults 65 years and older.
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MMWR study also found that during seasons when influenza A (H3N2) viruses were prominent death rates were more than double what they were during seasons when influenza A (H1N1) or influenza B viruses predominated.
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CDC does not know exactly how many people die from seasonal flu each year. There are several reasons for this. First, states are not required to report individual seasonal flu cases or deaths of people older than 18 years of age to CDC.
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Second, seasonal influenza is infrequently listed on death certificates of people who die from flu-related complications
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Third, many seasonal flu-related deaths occur one or two weeks after a person’s initial infection, either because the person may develop a secondary bacterial co-infection (such as bacterial pneumonia) or because seasonal influenza can aggravate an existing chronic illness (such as congestive heart failure or chronic obstructive pulmonary disease).
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Also, most people who die from seasonal flu-related complications are not tested for flu, or they seek medical care later in their illness when seasonal influenza can no longer be detected from respiratory samples. Sensitive influenza tests are only likely to detect influenza if performed within a week after onset of illness.
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In addition, some commonly used tests to diagnose influenza in clinical settings are not highly sensitive and can provide false negative results (i.e. they misdiagnose flu illness as not being flu.) For these reasons, many flu-related deaths may not be recorded on death certificates.