What is the difference between passive and active immunity?

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Whenever strange bacteria and pathogens discover their way into the body, they are generally destroyed by the immune system. Before getting to the immune system, the foreign material has to go through a few defense lines that your body has in place.

The first defense line in the human body against pathogens is through the barriers like skin, saliva, and a mucus layer. This layer is known as innate immunity.
The second defense line is via phagocytes that are produced by innate immunity.
The third defense line is adaptive immunity.

Passive and active immunity are the two adaptive immunity types.

The function of an immune system

The immune system limits or prevents a person from infection. When the immune system recognizes pathogens, it generally addresses an issue.

Whenever an immune system is not activated, problems like diseases and disorders arise.

What is active immunity?

Active immunity refers to the immunity where a human body develops its own antibodies whenever the body is exposed to a disease.

It generally allows the immune system to identify an illness that will trigger the body to fight against the disease.

It may sometimes provide life-long protection against the diseases and is often long-lasting.

Examples of Active Immunity

Whenever a body is exposed to pathogens, passive immunity is triggered.
Body exposure to some pathogen parts in a vaccine-like Live attenuated vaccine

What is passive immunity?

Passive immunity refers to an immunity type that is endowed when a person is provided with antibodies from outside.

It generally supports immediate protection but at the same time doesn’t guarantee long-term safety, just like the active one.

Examples of Passive Immunity

A baby receives antibodies from its mother during the pregnancy’s third trimester.
Breast milk comprises antibodies in addition to other abs.

Understanding the differences between Active and Passive Immunity

Parameters	Active Immunity	Passive Immunity
Protection Length	It provides long-lasting protection.	It provides short-term protection.
Immunological Memory	It generates immunological memory	It does not generate immunological memory.
Abs Production	Own body’s host will make the antibodies whenever exposed to the pathogens, lymphocytes from memory cells.	Here the host receives antibodies from some outside source.
Response speed	Active immunity has a slower response.	Passive immunity has a faster response.
Side effects	It has no side effects and does not cause any chemical reactions.	It may comprise of specific side effects when it is given externally.
Antigen exposure	It requires exposure to the antigen of a pathogen.	It doesn’t require any exposure to any infectious agent.
Immune system involvement	Here the immune system of an individual is actively involved in the entire process.	Here the immune system of an individual is not actively involved.
Natural Acquirement	Arises naturally when a person is exposed to a pathogen or an antigen.	Arises naturally when the fetus obtains antibodies from the mother across the placenta.
Artificial Acquirement	It confers artificially through the vaccines.	It confers artificially through the administration of preformed antibodies.
Components	T cells, B cells, and antigen-presenting cells	Here no immune cells are involved
Immunity Type	It involves both cell-mediated and humoral immunity.	Here the immunity is conferred only by ready-made antibodies.
Memory cell formation	It results in the formation of long-lasting memory cells.	Here memory immune cells are not formed.
Antibody production	It involves the antibody production that is induced by immunogen or infection.	Here no antibody is produced but directly transferred.
Durability	Here the protection offered is long-lasting.	Here the protection is only transient.
Secondary response	Here the first exposure leads to response and in the case of subsequent exposure to the same pathogen, a stronger and faster secondary response is established.	A secondary response is absent here.
Reactivation	It is reactivated by infection recurrence or revaccination.	Here the frequent administration is required for renewed protection.
Response Time	Here the protective response takes time to establish	Here no lag period is there so the protection is instant.
Use	Very effective for diseases prophylaxis	Artificial passive immunity is effective as a post-exposure remedy
Suitability	It is not suitable for the protection of immune-deficient or immune-compromised individuals.	It is useful in cases of immunodeficient, immune-compromised, or severe combined immunodeficiency.
Protection Effectiveness	It provides effective protection	Protection is less effective
Adverse effects	It can be implicated in autoimmune allergies and diseases but generally does not have any side effects.	A condition known as serum sickness can be an outcome of exposure to antisera.

Bottom Line!

The prominent difference between passive and active immunity is that active immunity is developed because of the antibody’s protection in a person’s own body.

In contrast, passive immunity is developed by the antibodies that are generated outside and then later on introduced in the body.

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