Immunisation refers to the process where the body induces immunity to a disease as a result of a vaccine. The World Health Organisation considers immunisation to be the most effective medical intervention to prevent deaths and reduce disease in communities.
Immunisation is the safest and most effective way of providing protection against childhood diseases. After immunisation, your child is far less likely to catch these diseases if there is an outbreak in the community. The benefit of protection against childhood diseases far outweighs the very small risks of immunisation. If enough people in the community are immunised, the infection can no longer be spread from person to person and the disease can die out altogether. This is how smallpox was eliminated from the world and why polio disappeared from many countries.