Immunization is a medical tool that makes an individual resistant to certain diseases or conditions. This is beneficial in controlling and eliminating various life-threatening diseases prevalent worldwide. Also known as vaccination, during immunization, you are being exposed to either modified or killed version of a virus or bacteria. This leads to an immune response in your body. Your body’s defence system develops antibodies against that particular bug to fight against it effectively the second time your body will get affected by that bug. After getting the vaccine, you may go through an array of mild symptoms like pain, swelling, headache, muscle and joint pain, mild fever etc. Rarely, any person develops serious side-effects.