Average and Median Ages of 2009 H1N1-Related Deaths in the United States, Spring and Fall 2009

More data released by CDC based on the H1N1 infections in the United States :

" What are the average and median ages of people in the U.S. who have died from 2009 H1N1?

Based on two CDC investigations of confirmed 2009 H1N1-related deaths that occurred during the spring and fall of 2009, the average age of people in the U.S. who died from 2009 H1N1 from April to July of 2009 was 40. The median age of death for this time period was 43. From September to October of 2009, the average age of people in the U.S. who died from 2009 H1N1 was 41, and the median age was 45.

How were the average and median ages of people in the U.S. who died from 2009 H1N1 in the spring and fall calculated?

Data from spring 2009 H1N1-related deaths was obtained from states, who were asked to provide information about all confirmed 2009 H1N1-related deaths that occurred from April to July, 2009. Data from fall deaths consisted of randomly selected patients that represent a proportion of all confirmed 2009 H1N1-related deaths occurring during September and October of 2009. The sample size requested from states for fall deaths was based on the population of the state and the number of deaths they were reporting (or that they were expected to report).

The data collected using this method of calculation have limitations. Although all confirmed 2009 H1N1-related deaths that occurred from April through July of 2009 were reported to CDC for these studies, only a representative proportion of those that occurred in September and October were reported. Therefore, many deaths that occurred in the fall months were not taken into consideration. This may have skewed the average and median ages of 2009 H1N1-related deaths for this time period."