There has been good data on the efficacy of vaccines given intradermally vs subcutaneously or intramuscularly. It actually seems to function superiorly in children and the elderly. I personally take my flu shot this way as I feel it also limits my systemic side effects.   0.1 ml of both the influenza vaccine (Fluogen) and the Herpes Zoster Vaccine (Varivax) in opposite arms seems to lessen the frequency and severity of recurrent upper respiratory tract illnesses.