What is meant by immunization: Immunization helps a human being build resistance to certain fatal diseases and it is a process through which this objective is achieved through injection with the help of serums or vaccines. Serums build immunity by multiplying antibodies directly into the blood stream. Vaccines help build immunity by making the human body to produce disease-fighting substances known as antibodies.  Immunization can be classified into two type’s namely active immunization which deals with the use of vaccines and passive immunization which involves using serums.

Active Immunization: Otherwise termed as vaccination, vaccines help build resistance to particular diseases by instructing the body’s immune system in the production of substances known as antibodies. When the actual disease affects a person, these antibodies help fight the disease causing organism and prevent the infectious disease from affecting the body. Vaccines are made in such a manner that they are powerful enough to produce antibodies in the human system but actually does not have enough of the organism causing the disease, to cause the disease. Vaccines are made up of the actual disease causing organism(virus or bacteria) which are killed or consist of live germs which are weakened so that it does not cause the disease. The disease causing organisms at time secrete poisonous substances out of which vaccines are made by chemically treating them and these are called as toxoids. Few other vaccines are made from parts of the live disease causing organism and certain vaccines are made out of live organisms which resemble disease-causing ones.

Many vaccines have been created to fight against dreadful diseased such as German measles or rubella, measles, influenza, mumps, meningitis, tetanus, yellow fever, whooping cough, poliomyelitis, pneumococcal pneumonia, rabies and diphtheria. Almost all vaccines are administered intravenous or injected into the body except for sabin polio vaccine which is administered orally.

Generally vaccines are provided only once to fight against a disease. But certain vaccines are administered several times at regular intervals to cultivate immunity against a disease commonly known as booster doses. Whooping cough, diphtheria and tetanus vaccines are combined together and given as one vaccine. Mumps, measles and German measles are also combined together. The effect of a vaccine begins about two weeks after administering a dose and resistance to the disease is formed.

Eventhough vaccines cultivate resistance towards a disease, about ten percent of the population which is vaccinated may not develop immunity. Vaccines can also cause adverse effects in very few individuals(about 1 in 2.7 million person).

Passive Immunization: This involves administering serum to a person instead of a vaccine and this provides instant protection against a infection. A serum contains antibodies which have been grown in an animal or another person. But the protection exists only for some time and as the antibodies disappears gradually, its effect diminishes. Serums are administered to people who have already got the disease like measles, hepatitis, tetanus and rabies. Vaccines would react slowly for these people. Serums are also administered where a vaccine has not been made for a particular disease.