U4 AOS1 Topic 5: Immunity Acquisition

Immunity can be classified as natural and artificial immunity. Natural immunity is not developed by medical interference whereas; artificial immunity is developed by medical interference or by vaccines. Based on strategy used to develop the immunity, it can be further classified as active and passive immunity. In active immunity, a body produces its own antibodies against an antigen whereas, in passive immunity the antibodies against a specific antigen are administered from outside into the body.

Natural active immunity

It is the immunity which is developed when a person’s body produces antibodies against an antigen. It is called as “natural” because the immunity is developed without medical interference and “active” because the body produces its own antibodies. For example, a person’s body fights against common cold virus by producing antibodies.

Natural passive immunity

It is the immunity which is developed when a person receives antibodies from outside the body. It is called as natural because this immunity is developed without medical interference and passive because the antibodies are administered from outside the body. For example, a baby gets antibodies produced by a mother’s body via breastfeeding.

Artificial active immunity

It is the immunity which is developed when a person’s body produces its own antibodies against antigens that are administered from outside the body. It is called as artificial because immunity is developed with medical interference i.e. via vaccines and active because the body produces its own antibodies. For example, vaccine against polio virus contains dead polio virus or the antigens of polio virus which once administered in the body causes the body to produce antibodies against these antigens.

Artificial passive immunity

It is the immunity which is developed when a person receives antibodies from outside the body. It is called as artificial because immunity is developed with medical interference and passive because antibodies are administered from outside the body. For example, antivenom which is antibodies against venom is administered into a person who has been bitten by snake.

Vaccination

Vaccines are weakened or dead pathogens which are administered into the body to induce an immune response.  A vaccine can contain one of the following components which a person’s immune system can recognize as an antigen:

1.   Weakened or attenuated pathogen

2.   Dead or inactive pathogen

3.   Harmless altered toxins called toxoids

4.   Specific surface proteins of pathogen

5.   RNA from pathogen that can make pathogen proteins.

When a vaccine is administered into a person’s body, there are two responses. After the first vaccination, antibodies and memory cells are produce by the body. This is called as primary immune response which is quite slow. After the second vaccination, memory cells already present in the body quickly recognize these antigens and a secondary immune response takes place. Vaccination program also known as vaccination schedule designs a series of vaccines to induce long term immunity.