| Active Immunity | Passive Immunity |
| Active immunity is usually long-lasting, sometimes life-long. It is produced by the antibodies of the host in response to direct contact with an antigen | Passive immunity lasts only for a few weeks or months. It is produced by the introduction of antibodies from outside into the host |
| It produces an immunological memory | It does not produce immunological memory |
| When the antigens enter the body, antibodies and other specialised lymphocytes are produced | Antibodies are introduced from an external source. For instance, a mother introduces antibodies to a fetus through the placenta and to an infant via mother’s milk. |
| There are no side-effects | It may cause reactions |
| Immunity does not occur immediately | Immunity develops immediately |
Difference Between Active Immunity and Passive Immunity
Active Immunity:
- Mechanism: Occurs when the body is exposed to a pathogen or vaccine, leading to the production of antibodies and memory cells.
- Duration: Long-lasting, often for years or even a lifetime, due to the development of immunological memory.
- Examples: Immunity gained after recovering from an illness (natural) or through vaccination (artificial).
Passive Immunity:
- Mechanism: Involves the transfer of antibodies from another source, such as mother to fetus through the placenta or through antibody-containing treatments.
- Duration: Short-term, typically lasting a few weeks to months, as the body does not develop memory cells.
- Examples: Maternal antibodies passed to the baby, immunoglobulin treatments for certain infections.
Conclusion:
Active immunity involves the body’s own adaptive response, providing long-term protection, while passive immunity provides immediate but temporary protection through externally acquired antibodies. Both types are crucial in different scenarios for disease prevention and management.
Overview
- Active immunity is attained by exposure to a pathogen. This leads to the production of antibodies in the body. The antigens present on the surface of the pathogens act as markers that bind to the antibodies.
- Passive immunity is acquired when antibodies are introduced into the body from an external source (usually through vaccines). It provides a quick response to the infection.
