You do realize that a flu vaccine is just a weakened version of the virus. So actually your friend came down with it the day he got injected. That is the whole point of the vaccine, to build up your immunity with a weaker virus before you come in contact with a full strength strain but people still have different reactions to the vaccine and some will have zero to minimum reaction and some might have the same response as to the full strength strain.duckfi8 said:And oen of the reasons why I did not want to get it was because someone I work with got it and he came down with the flu the next day.