I used to catch the flu about once every three years, and I was miserable for at least a week. Once,in Mexico, for a month.
I am not teaching, but I do mingle with people regularly, in my exercise classes and the supermarket and other places.
The flu study documents all the possible contraindications, and other than a sore arm for maybe a day, I have suffered for none of them. I also feel that I am doing a good turn as well, since the flu study is intended for seniors, who really need a flu vaccine as effective as possible. Without actual studies, these vaccines would be much harder to develop.
I also take a Vitamin D pill once a day, multivitamins, Niacin and fish and flaxseed oil.