What is immunity achieved through infection, vaccination, or antibody transfer from an immune donor called?

The term that describes immunity acquired through infection, vaccination, or antibody transfer from a donor is known as acquired immunity. Acquired immunity develops as a response to specific pathogens and is characterized by the immune system's ability to remember and respond more effectively to agents previously encountered.

When someone becomes infected, their immune system produces antibodies specific to that pathogen, leading to recovery and a form of memory that can provide long-lasting protection. Similarly, vaccinations introduce a harmless part of the pathogen (like a protein or an inactive form), prompting the immune system to build defenses. Additionally, antibodies can be transferred from one individual to another, such as from mother to baby, which also contributes to this type of immunity.

In contrast, the other options refer to different concepts of immunity. Passive immunity is temporary and involves the direct transfer of antibodies without an immune response being activated in the host. Natural immunity refers to the immunity that occurs naturally through infection or recovery from a disease. Innate immunity is the body’s first line of defense, providing immediate but non-specific responses to pathogens, which contrasts with the more tailored responses associated with acquired immunity.