How often have we heard; "Let's go see what the dictionary says?"
So here's, Medical dictionary info and . . . WIKIPEDIA too?
OK, let's GO SEE! 👍
A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease.
a suspension of attenuated or killed microorganisms (viruses, bacteria, or rickettsiae), administered for prevention, amelioration, or treatment of infectious diseases.
Link one @ medical-dictionary.thefreed...
Link two (Trends; This section needs to be updated. June 2018g) @ en.wikipedia.org/wiki/Vaccine
Enjoy 😛