What defines natural immunity?

Natural immunity refers to the body's inherent ability to fight off pathogens, and it primarily develops through exposure to infectious agents, leading to the production of antibodies and activation of immune cells. This process occurs without medical intervention, meaning that individuals can gain immunity from naturally encountering pathogens in their environment.

The correct answer indicates that natural immunity is the result of the immune system's responses developed through real-life exposure to diseases, allowing for a more robust defense against future infections. In contrast, immunity acquired through vaccinations is classified as artificial immunity, where a weakened or inactive form of the pathogen is introduced deliberately to stimulate an immune response. The concept of inherited immunity since birth applies more accurately to genetic predispositions or maternal antibodies passed to the infant rather than the definition of natural immunity. Environmental factors can influence immunity, but they are not what define natural immunity itself; instead, they may play a role in the overall immune function and health of an individual.