Influenza is a highly contagious viral infection that affects mainly the nose, throat, chest and lungs. The flu may cause mild to severe illness, and may even lead to death in the very young, the elderly, and those with other serious medical conditions.
CDC recommends a yearly flu vaccination as the first and most important step in protecting against the flu. The U.S. 2010-2011 seasonal influenza vaccine will protect against an H3N2 virus, an influenza B virus, and the 2009 H1N1 virus that emerged last year to cause the first global pandemic in more than 40 years and resulted in substantial illness, hospitalizations and deaths. Seasonal 2010-11 vaccine has begun shipping from manufacturers and CDC recommends that everyone 6 months and older get a 2010-2011 flu vaccine for the upcoming season as vaccine is available. --Source Centers for Disease Control and Prevention