What is the difference between active and passive immunity?

Active immunity and passive immunity are two distinct types of immune responses that the body can develop.

Active immunity occurs when an individual’s immune system is exposed to a pathogen—either through infection or vaccination—leading to an immune response. This response includes the production of antibodies and memory cells that will allow the body to recognize and combat the pathogen in future encounters. The key characteristic of active immunity is that it requires time to develop as it depends on the body’s own immune response building against the specific pathogen. This process can last for many years, often resulting in long-lasting protection.

Passive immunity, on the other hand, refers to the short-term immunity gained from antibodies that are transferred from another source, rather than produced by the individual’s own immune system. This can occur naturally, as when a mother passes antibodies to her baby through breast milk or across the placenta, or artificially, as in the case when antibodies are administered through serum or immunoglobulin injections. Since this type of immunity does not involve the host’s immune system actively responding to an antigen, it provides immediate protection but does not confer long-lasting immunity because the newly introduced antibodies will eventually degrade and get cleared from the body.

The distinction lies in how immunity is acquired and the duration of protection. Active