Definition and Types of Immunity

What is Immunity?

Immunity is a condition of being able to resist a particular disease especially through preventing the development of pathogenic microorganisms or by counteracting the effects of its products. It is the capability of the body to resist harmful microorganisms or viruses from entering it. The healthy immune process is capable to recognize invading viruses, bacteria and also produce antibodies to destroy or disable them. It is the ability of the body to restrict dangerous microorganisms or viruses from entering it.

Types of Immunity:  

There are four types of the immune system which are explained below:

1. Innate (Natural) Immunity:

It is the natural resistance components such as intact skin, salivary enzymes, and neutrophils, natural killer cells, which provide an initial response against infection that is present in an individual at birth before exposure to a pathogen or antigen.

2. Adaptive (Acquired) Immune System:

It is that which develops antibodies after an attack of an infectious disease or by a pregnant mother passing through the placenta to a fetus or by vaccination.

3. Active Immunity:

It refers to the method of exposing the body to an antigen for generating an adaptive immune response. The response takes days/ weeks to develop but may be long- lasting. For example recovery from Hepatitis-A virus gives a natural active immune response that usually leading lifelong protection. Similarly, the administration of two doses of Hepatitis-A vaccine generates an acquired active immune response which leads to long-lasting defense.

4. Passive Immunity:

It refers to the process of imparting IgG antibodies to keep safe against infection. It gives immediate, but short-lived protection such as several weeks to 3 or 4 months at most. It occurs during pregnancy. The transfer of maternal tetanus antibody (mainly IgG) across the placenta provides passive immunity to a newborn baby for several weeks/ months until such antibody is degraded and lost.

Maria Mona

Maria Khatun Mona is a Founder and Editor of Nursing Exercise Blog. She is a Nursing and Midwifery Expert. Currently she is working as a Registered Nurse at Evercare Hospital, Dhaka, Bangladesh. She has great passion in writing different articles on Nursing and Midwifery. Mail her at “maria.mona023@gmail.com”