What characterizes passive immunity?

The characteristic that defines passive immunity is the provision of antibodies from an external source. This type of immunity occurs when a person receives antibodies that were produced by another individual or organism, rather than producing them through their own immune response. This can occur naturally, such as when a newborn acquires antibodies from the mother through breastfeeding or the placenta, or artificially, through the administration of immune globulin or antibody-containing serum.

In contrast, passive immunity is temporary because the body does not generate its own immune response or memory cells in response to the received antibodies. Therefore, while it offers immediate protection, it typically lasts only a short period, often weeks to months, hence distinguishing it from other forms of immunity, such as active immunity, which develops after exposure to a pathogen or vaccination.