What is Passive Immunity?
Passive immunity refers to the temporary protection against infectious diseases that is acquired through the transfer of
antibodies from another individual or species. Unlike
active immunity, which is developed through exposure to a pathogen or through vaccination, passive immunity is immediate but short-lived.
How is Passive Immunity Acquired?
There are two primary ways to acquire passive immunity: naturally and artificially.
Natural passive immunity occurs when antibodies are transferred from a mother to her infant through the placenta during pregnancy or through breast milk after birth. On the other hand,
artificial passive immunity is achieved through the administration of antibodies in the form of immunoglobulins or antiserum, often used in medical settings to provide immediate protection against specific infections.
What are the Benefits of Passive Immunity?
Passive immunity provides immediate protection, which is especially critical in situations where quick intervention is necessary, such as following exposure to a
pathogen or in the case of immunocompromised individuals. It can be life-saving during outbreaks or when dealing with
emerging infectious diseases where no vaccines are available.
Limitations of Passive Immunity
Despite its immediate effects, passive immunity has significant limitations. The protection offered is temporary, generally lasting only a few weeks to months, as the introduced antibodies are eventually degraded by the body. Furthermore, passive immunity does not result in the formation of
memory cells, so the individual remains susceptible to future infections by the same pathogen.
When is Passive Immunity Utilized in Medical Practice?
Passive immunity is often used in clinical practice for both prophylactic and therapeutic purposes. It is commonly administered to individuals exposed to
rabies,
tetanus, or
hepatitis B, among others. Additionally, it can be used in treating certain infectious diseases like
botulism or
diphtheria.
What are the Sources of Antibodies for Passive Immunity?
The antibodies used for passive immunity can be derived from human donors who have recovered from the disease or have been vaccinated, or from animals such as horses, which have been immunized against specific pathogens. The choice of source depends on the disease and the availability of
immunoglobulins.
Risks Associated with Passive Immunity
While passive immunity is generally safe, it carries some risks. Recipients may experience allergic reactions, including
anaphylaxis, especially with animal-derived antibodies. There's also the potential for transmission of infections if the antibodies are not properly screened.
Future Perspectives of Passive Immunity
Advancements in biotechnology are improving the safety and efficacy of passive immunity.
Monoclonal antibodies, which are engineered to target specific pathogens, offer a promising future by reducing the risks associated with traditional antibody sources and potentially extending the duration of immunity.
Conclusion
Passive immunity plays a vital role in the management and prevention of infectious diseases, offering immediate protection when time is of the essence. While it is a valuable tool in medical practice, its temporary nature and associated risks emphasize the importance of complementing it with long-term strategies like vaccination and public health measures.
