# 4002
Just posted on the CDC website, the long awaited estimates of the impact of the H1N1 pandemic in the United States. These numbers are through Oct 17th.
These are not actual counts, but a range of estimates. We simply lack the surveillance and reporting ability to count influenza-related deaths in this country.
You can find previous discussions on the reasons why the official counts under represent the true number of cases, hospitalizations, and deaths at:
When No Number Is Right
Dead Reckoning
Numbers Don’t Tell The Whole Story
A Decided Lack Of Data
Measuring The Severity Of A Pandemic
Arizona & Illinois Report Swine Flu Related Deaths
The following are excerpts from a much larger web page explaining how the CDC derived these numbers. Follow the link to read it in its entirety.
CDC Estimates of 2009 H1N1 Influenza Cases, Hospitalizations and Deaths in the United States, April – October 17, 2009
November 12, 2009, 1:00 PM ET
The Numbers
- CDC estimates that between 14 million and 34 million cases of 2009 H1N1 occurred between April and October 17, 2009. The mid-level in this range is about 22 million people infected with 2009 H1N1.
- CDC estimates that between about 63,000 and 153,000 2009 H1N1-related hospitalizations occurred between April and October 17, 2009. The mid-level in this range is about 98,000 H1N1-related hospitalizations.
- CDC estimates that between about 2,500 and 6,000 2009 H1N1-related deaths occurred between April and October 17, 2009. The mid-level in this range is about 3,900 2009 H1N1-related deaths.
Under-Counting of Flu-Related Deaths
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.
- Second, seasonal influenza is infrequently listed on death certificates of people who die from flu-related complications.
- 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 a staph infection) or because seasonal influenza can aggravate an existing chronic illness (such as congestive heart failure or chronic obstructive pulmonary disease).
- 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. Influenza tests are most likely to detect influenza if performed soon after onset of illness.
- For these reasons, many flu-related deaths may not be recorded on death certificates.
These are some of the reasons that CDC and other public health agencies in the United States and other countries use statistical models to estimate the annual number of seasonal flu-related deaths. (Flu deaths in children were made a nationally notifiable condition in 2004, and since then, states have reported flu-related child deaths in the United States through the Influenza Associated Pediatric Mortality Surveillance System).
