Active vs Passive Immunity: Difference and Comparison

When our immune system or immunity senses infections, it responds to the situation. Infections and illnesses can occur when the immune system is not activated.

Problems such as allergic responses and autoimmune illness emerge when an immune system is aroused without a true threat or is not switched down when a threat has passed.

Active immunity and passive immunity are two types of immunity.

Key Takeaways

1. Active immunity is long-lasting protection resulting from the body’s immune response to an antigen, while passive immunity offers temporary protection by transferring antibodies from another source.
2. Active immunity can be acquired naturally through exposure to a pathogen or artificially through vaccination. In contrast, passive immunity can be acquired through maternal antibodies or by receiving antibody-containing blood products.
3. Active immunity takes time to develop, as the body needs to recognize, respond to, and remember the antigen. In contrast, passive immunity provides immediate protection but wanes over time as the borrowed antibodies break down.

Active Immunity vs Passive Immunity 

The difference between active immunity and passive immunity is that active immunity is a type of immunity that has developed in an individual’s body as a response to infections or with the help of vaccinations, whereas passive immunity is developed by transferring the antibodies to another individual through either placenta, breast milk, or injections. 

Active immunity refers to a person’s body’s immediate response to infections. It is also induced when it is exposed to a foreign antigen, such as the antigen found in microorganisms.

It also refers to a person’s adaptive reaction after coming into touch with a certain infection or antigen. This type of immunity does not develop instantly. 

Passive immunity is immunity conferred by an individual through the transmission of serum or lymphocytes. They also get it from someone who is highly vaccinated.

It also takes effect instantly and without delay. Furthermore, it is short-lived. In other words, it may only last a few months. 

Comparison Table

Parameters of Comparison	Active Immunity	Passive Immunity
Duration of Protection	Long-term	Short-term
Response Speed	Slow	Fast
Immunological Memory	It has an immunological memory.	It doesn’t have any immunological memory.
Antibodies	Produced in the body	Introduced from an external agent
Natural Acquirement	Infections	Through the placenta, breast milk
Artificial Acquirement	Vaccinations	Administration of antibodies through injections.
Immunity Type	Humoral and cell-mediated	Immunity is acquired through readymade antibodies.
Suitability	It is not suitable for immuno-compromised people.	It is suitable for immuno-compromised people.
Secondary Response	A faster and stronger secondary response.	No secondary response
Components	Antigen-presenting cells along with B and T cells	No immune cells included
Lag Period	Present	Absent
Side Effects	Generally, has no side effects	It May have some side effects

What is Active Immunity? 

Active immunity is immunity to a pathogen that develops after exposure to the infection. Immunity does not develop immediately after exposure to a pathogen.

Active immunity can take days or weeks to develop following the first encounter.  

When the body is exposed to a new disease agent, B cells, a kind of white blood cell, produce antibodies that aid in destroying or neutralising the pathogen.

Antibodies are y-shaped proteins with the ability to attach to antigens on poisons or infections. Antibodies are disease-specific, which means they protect the body from only one type of disease agent.  

Furthermore, the protection it provides is long-lasting. The protective response takes longer to build because of the lag period.

Finally, a recurrence of infection or revaccination can reawaken it. 

As a result, it could take days or weeks for it to manifest after the initial exposure. However, once it develops, the protection it provides can last a lifetime.

Furthermore, it can occur in one of two ways: naturally or by immunization. 

When a body is exposed to a disease, it develops its own antibodies, which is known as immunity. It enables the immune system to recognize a disease, which then prompts our bodies to fight it.

It is frequently long-lasting and may provide disease protection for the rest of our lives. 

What is Passive Immunity? 

The antibody is produced without the involvement of immune cells in passive immunity. Furthermore, because it transmits directly, there is no antibody generation.

Furthermore, memory immune cells do not form. 

In addition, there is no alternative response available here. For continued protection, it must be re-administered on a regular basis.

It’s then useful in cases of immune deficiency, immunodeficiency, or severe combined immunodeficiency. 

Furthermore, it is a very useful way to give resistance without having to wait for the active immune response to develop. It does not necessitate prior disease agent exposure.  

It is a sort of immunity that is given to a person when they are given antibodies from outside sources. It gives temporary protection but not the long-term protection that active immunity provides. 

Passive immunity can be acquired in a variety of ways and save one’s life.

Because antibodies aren’t replaced as frequently as they are in someone whose immune system is responding in a very healthy and regular way, passive immunity is short-lived.

Passive immunity can be acquired in a variety of ways:

• Maternal antibodies: They can be in the form of transferring through the placenta and circulation during pregnancy and through breast milk after childbirth. 
• Immunoglobulin treatments 

Main Differences Between Active and Passive Immunity 

1. Active immunity gives your body long-term protection, whereas passive immunity gives your body short-term protection. 
2. Active immunity’s response speed is slower than passive immunity’s response speed. 
3. Active immunity does not produce an immunological memory, whereas passive immunity does. 
4. The antibodies are produced in the body during active immunity, whereas in passive immunity, the antibodies are introduced by an external agent. 
5. Active immunity is acquired through exposure to infections naturally or through vaccinations artificially. Passive immunity is acquired through the placenta or breast milk, naturally and through the administration of antibodies artificially. 
6. Active immunity is a humoral and cell-mediated immunity, whereas passive immunity is an immunity acquired through readymade antibodies. 
7. Active immunity is unsuitable for immuno-compromised or immuno-deficient people, whereas passive immunity suits them. 
8. Active immunity tends to have a faster and stronger secondary response, whereas passive immunity has no secondary response and needs to be re-administered. 
9. Active immunity consists of antigen-presenting cells and B and T cells. On the other hand, passive immunity has no immune cells. 
10. A lag period is present in active immunity, whereas, in passive immunity, it is absent. 
11. Active immunity has no side effects usually. Passive immunity may have some side effects or reactions. 

References

1. https://academic.oup.com/occmed/article-abstract/57/8/552/1474357 
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2131512/