To many people, the word "inoculate" relates specifically to vaccination, in that to inoculate someone means to administer a vaccine to that person. While that definition of the word is true, the word "inoculate" also has a more general meaning in the field of microbiology, one that still applies to the process of vaccination, but isn't related at all to the goal of bolstering a person's immune system.
According to microbiologists, to inoculate means simply to introduce -- or insert -- one substance into another. For example, you could inoculate a bacteria culture with a certain chemical compound -- in other words, you introduce the chemical compound into the bacteria culture. This holds true for vaccinations. If the doctor inoculates you for polio, he introduces a weakened form of polio into your system via injection. The inoculation refers only to the introduction of the polio into the body. It does not pertain to the body's response thereafter.