CBSE Class 12-science Answered

Immunisation means developing resistance to disease-producing germs or their toxins by introducing killed germs or germ substances to induce the production of specific antibodies. It protects people against harmful infections before they come into contact with them in the community.

Now, if a person is actively or passively immunized for common diseases like polio, diphtheria, tetanus, measles, typhoid, pertussis and tuberculosis, that person will not contract these diseases because the antibodies to fight off these infections are already present in his body.

However, if the person is infected with a deadly microorganism for which the person has not been immunized, then immunization will not form the first line of defense and thus, will not be able to provide the fastest immune response. In this case, antibiotic administration against that specific microorganism will be able to provide the fastest immune response.