What is Immunity?

Immunity is the body’s ability to prevent and fight off the invasion of germs, bacteria, viruses and various other pathogens. These infectious agents can cause severe harm to the body as they carry diseases. When these pathogens invade the body, an immune response is activated, which fights the antigens that the pathogens carry. White blood cells perform the function of killing the pathogens in the immune system.

Immunity is very critical to maintain. Failing to do so will result in irreversible damage to the body and sometimes may even result in death. In times of a pandemic, it is all the more important to maintain healthy immunity and keep it unaffected.

Immunity can be Innate and Acquired / Adaptive

Innate Immune System - The First Line of Defence

The innate Immune system is the ‘first to fight’ against an invading pathogen. It fights pathogens by activating cells that detect and destroy invaders. It also informs the acquired/adaptive immune system of invading pathogens, which follows the information given by the first line of defence. Our Innate immune system is what we are born with and consists of all of our basic immune responses such as inflammation, sneezing and coughing.

The Innate Immune system does not fight specific pathogens like the acquired immune system does. Innate immune responses depends on the ability to recognize the nature of invaders which are not present in a normal human body.

Acquired Immune System - Specific Defence

As a pathogen invades, body creates immunological memory to protect itself against this pathogen the next time it invades. The immune system providing protection against specific pathogens is the result of the Acquired Immune System. Acquired Immunity is also known as adaptive immunity. When a person is exposed to a pathogen or through a vaccine (attenuated or dead pathogen), the body’s cells learn to recognise them and store this information to be recalled later. This information is used to produce antibodies that specifically know how to destroy the pathogens in case they enter the body again. Vaccines are the prime example of the Acquired Immune System. They help the body remember disease causing pathogens.

Types of Immunity

1) Active Immunity: is the most common form of acquired immunity. It is activated when a disease causing pathogen enters the body. Active immunity can be acquired through Natural means, where the person contracts the actual disease and falls sick, or through a vaccine.

A) A Natural Immunity: is built up after the patient has acquired the actual disease or infection. The body learns to recognise the pathogen and creates specific antibodies that kill them. This information is stored as immunological memory and is used to kill the pathogen in case it enters the body again.

B) Vaccine Induced Immunity: is acquired through a vaccine, which administers a weakened or killed form of the disease organism into the body. This creates antibodies in the person’s bodies that kill the pathogen in the case of an invasion.

2) Passive Immunity: is acquired when a person is given antibodies from someone else and does not produce them in his/her own body. In this form of immunity, the body only recognises the pathogens for a small period of time, after which it forgets and the person is at risk of falling sick. Passive Immunity can be built up rapidly, whereas Active immunity takes several weeks to build up. Examples of the body receiving passive immunity are:

A) Mother’s Breast Milk: When a baby is born, it has a lot of deficiencies in its immune system and the mother’s milk is primarily responsible for plugging these deficiencies. Mother’s milk contains antibodies which protect the infant against any pathogens it may contract in the first few months of life.

B) Blood Products: Blood products such as Immunoglobulin contain antibodies which when given, protect the body against a specific pathogen or disease.

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