What is immunization?
‘Vaccination’ refers simply to the administration of a vaccine, whereas ‘immunization’ means that the person developed immunity as a result of being vaccinated (or immunized).
The principle in immunization is to introduce a harmless preparation of the antigens from an infectious agent into the body of a person, who becomes immune to the infectious agent as a result. The harmless preparation of antigens is called a vaccine (pronounced ‘vax-een’). It is made from killed or weakened viruses or bacteria, or antigens extracted from the infectious agents. Immunization should happen before the person develops a vaccine-preventable infection, so vaccines are usually given to babies and young children, either by injection or swallowing liquid drops. However, you should note that there are many communicable diseases that cannot be immunized against at the present time, because a suitable vaccine does not yet exist.
Can you think of two very important communicable diseases which do not yet have a vaccine?
You may have thought of malaria and HIV/AIDS.