Most experts believe that flu viruses spread mainly bydroplets made when people with flu cough, sneeze or talk. These droplets canland in the mouths or noses of people who are nearby. Less often, a personmight also get flu by touching a surface or object that has flu virus on it andthen touching their own mouth, eyes or possibly their nose.
http://www.cdc.gov/flu/pdf/freeresources/family/A_Flu_Guide_For_Parents.pdf