Difference Between Active and Passive Immunity (With Table)

Immunity refers to the body’s capacity to eliminate foreign elements and germs to prevent infection. The epidermis, mucous layers, and saliva are the first line of defense against infections in the human body. When an immune system is awakened without an actual threat or is not shut down once a threat has passed, problems such as allergic reactions and autoimmune diseases develop. Immunity may be divided into two categories: active and passive.

Active vs Passive Immunity

The main difference between Active and Passive immunity is that Active immunity is based on antibodies created within the body. In contrast, passive immunity is based on antibodies made outside the body and then delivered into the body.

“active immunity” describes the body’s early reaction to pathogens. It may also relate to a person’s adaptive reaction to a certain sickness or antigen exposure. When it is exposed to a foreign antigen, such as that present in bacteria, it is also triggered. Immunity like this takes time to build.

Immunity supplied by a person through the transfer of serum or lymphocytes is known as passive immunity. They might potentially get it from someone who is extensively vaccinated. It also works immediately and without delay. Furthermore, it is just temporary. It may only survive a few months, to put it another way.

Comparison Between Active and Passive Immunity

What is Active Immunity?

Active immunity occurs when the body’s immune system generates a response to an antigen, such as a virus, bacteria, or foreign substance, and develops the ability to recognize and defend against it in the future. This immunity is characterized by producing antibodies and memory cells that “remember” the antigen, providing long-lasting protection.

The process of acquiring active immunity involves the following steps:

1. Exposure to Antigen: The immune system encounters a foreign antigen through infection or vaccination. The antigen is recognized as a potential threat.
2. Immune Response: The immune system’s white blood cells, particularly B cells, produce antibodies tailored to target the antigen. These antibodies bind to the antigen and help neutralize or eliminate it.
3. Memory Cells: Memory B and T cells are formed after the infection or vaccination. These cells “remember” the antigen and remain in the body for an extended period.
4. Long-Term Protection: If the same antigen re-enters the body later, the immune system can rapidly and effectively respond. This is the basis for immunity against many diseases, as the body is better equipped to fend off subsequent infections.

Active immunity is considered more durable and long-lasting than passive immunity, which involves the transfer of pre-formed antibodies, as it allows the body to defend itself against future encounters with the same antigen. This principle is the basis for the effectiveness of vaccines, which stimulate the immune system to produce an active immune response without causing the disease itself.

What is Passive Immunity?

Passive immunity is acquired when a person receives pre-formed antibodies or immune cells from an external source rather than producing them within their own body. These antibodies or cells are obtained from another organism, such as a human or an animal, and are then transferred to the individual needing protection. Passive immunity provides immediate but temporary defense against specific pathogens or toxins.

There are two main ways passive immunity can be acquired:

1. Natural Passive Immunity occurs naturally when a newborn receives antibodies from its mother, through the placenta during pregnancy or breast milk after birth. These maternal antibodies temporarily protect infants against certain diseases until their immune system matures.
2. Artificial Passive Immunity: This is induced through medical intervention. Pre-formed antibodies, such as those harvested from the blood of individuals who have recovered from a particular disease or produced in a laboratory, are administered to a person as a treatment or preventive measure. This is done in cases of emergency or when rapid protection is needed, like in the case of snakebite antivenom or the treatment of certain infections.

Passive immunity, while providing immediate protection, is temporary because the transferred antibodies eventually degrade and are eliminated from the recipient’s body. In contrast, active immunity is developed by the body’s own immune system and provides long-lasting protection, through vaccination or exposure to pathogens.

Main Differences Between Active and Passive Immunity

1. During active immunity, antibodies are created in the body, whereas antibodies are delivered from an external source during passive immunity.
2. The active immunity reaction time is slower than the passive immunity response time.
3. Passive immunity protects your body for a short period of time, but active immunity protects it for a long time.
4. Passive immunity, in contrast to active immunity, produces an immunological memory.
5. In most cases, active immunity comes with no negative consequences. There may be some negative side effects or responses from passive immunity.
6. Active immunity has a lag period, but passive immunity does not.

Conclusion

Antibodies in our immune provide us with protection from foreign agents. Active and passive immunity are two highly significant forms of immunity in a person’s life. We are considered to have active immunity when our immune system protects us against disease. Active immunity can develop spontaneously or as a result of vaccination. We are considered passive immunity when protected against a virus by someone else’s protection.

References

1. https://www.ncbi.nlm.nih.gov/books/NBK513280/
2. https://academic.oup.com/occmed/article-abstract/57/8/552/1474357