Vaccine

Synonyms

Immunization, Vaccination

Definition

A vaccine is typically a suspension of a pathogenic microorganism, such as virus or bacterium, used to stimulate the body’s immune system and result in defense against the microbe-causing disease.

Introduction

There are a tremendous number of infectious organisms threatening human health including viruses, bacteria, fungus, and parasites in the surrounding environment. To cope with the infectious risks of these pathogens, living organisms have acquired and evolved immune system as a self-protecting mechanism. The primary role of the immune system is to recognize a nonself agent as foreign, eliminate it, and remember it in case the agent later attempts reentry into the body. A bunch of cells called immune competent cells, which include dendritic cells, monocytes, macrophages, and lymphocytes, form ingenious networks and induce effective immune responses to maintain this self-protecting system. In addition of naturally occurring immune...