Application of a little commn sense would get one thinking. The flu is contracted through the eyes, nose, mouth. It is not contracted by a hole in the arm. A vaccination against a disease that is contracted through the mucus membranes is safest when given that way. How can one explain that one of the single most effective vaccines is the tetanus shot? And the most long lasting, at that. You get tetanus through a puncture wound. Not the flu. My 2 cents.