On October 5, 2004, the Centers for Disease Control was notified by Chiron Corporation that none of its influenza vaccine would be available for distribution in the United States for the 2004'“05 influenza season. This will reduce by approximately one half the expected supply of flu shots available in the United States for the 2004'“05 season.
Following is a link to the CDC's Web page on its recommendations in light of the flu shot shortage: https://www.cdc.gov/flu/protect/whoshouldget.htm
What's behind the vaccine shortage? The Pittsburgh Tribune-Review took a stab at finding out. To read their article, click here. (Article may no longer be available.)