My vet has always told me to rub the vaccination site for a few minutes following the vaccination. I assume that is to prevent a reaction? When I've gotten a flu shot myself, I also have been advised to rub the site to prevent soreness. Not sure what this actually does.
When I was young, I admired clever people. Now that I am old, I admire kind people. -Abraham Joshua Heschel, theology professor (1907-1972)