An individual's self-esteem can be affected by genetics as well as environmental factors, and poor self-esteem often begins in childhood. A person who experiences an abusive childhood or who didn't get enough approval from authority figures, feels his or her self-worth was based on achievements or feels excluded will often have poor self-esteem.
<em>Vaccines work by simulating an illness to help establish immunity. However, while this sort of infection nearly never produces sickness, it does trigger the immune system to create T-lymphocytes and antibodies. The imitation illness can sometimes induce modest symptoms, like as fever, after receiving a vaccination.</em>
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<em>- RobertOnBrainly</em>