Question

Why do vaccines build up immunity?

Answer 1

Often, multiple doses are necessary tobuild up and/or maintain immunity. Toxoid vaccines prevent diseases caused by bacteria that produce toxins (poisons) in the body. In the process of making these vaccines, the toxins are weakened so they cannot cause illness.

Answer 2

 
The body raises its temperature when it is exposed to the weakened or dead form of a pathogen. 

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