Answer:
vaccination
Step-by-step explanation:
The vaccination has been one of the most revolutionary inventions in the medical field. This invention helped protect people from numerous diseases, some being totally neutralized, while some having only minor effects on the human body. The vaccination basically is a way of enhancing the immune system of the body by injecting in it a weakened form of the pathogen. In this way, the weakened form of the pathogen is not capable to harm the body, and the body is not fighting against it, but instead the pathogen becomes part of the body and its defense mechanism, so when the pathogen strikes, the body has a counter attack and defeats it.