How the Vaccine works?

The Vaccine works by training the immune system to recognise and combat pathogens. Our body is introduced by the certain molecules of pathogens, called antigens, to trigger immune response. 

        These antigens are injected in human body, in the response our immune system starts producing antibodies that recognise the pathogens. If the pathogen appears in the body in future, these antibodies recognise  the pathogen immediately and attack aggressively well before the pathogen is disseminated and causes sickness