What best describes passive immunity?

• A. Immunity acquired through natural infection
• B. Immunity received from maternal antibodies
• C. Immunity developed post vaccination
• D. None of the above

Answer: (B)

Passive immunity is best described as immunity received from maternal antibodies. This form of immunity occurs when antibodies are transferred from one individual to another, providing immediate but short-term protection against pathogens. In the case of maternal antibodies, a mother can pass these antibodies to her fetus during pregnancy through the placenta or to her infant through breast milk after birth. This helps to protect the newborn in the early months of life when their own immune system is still developing.

Other forms of immunity, such as those acquired through natural infection (like recovering from a disease) or those developed post-vaccination (which stimulate the body to produce its own antibodies), are examples of active immunity rather than passive. Active immunity involves the immune system actively engaging and producing its own defense mechanism, as opposed to receiving ready-made antibodies from another source.