ANATOMY

Detailed explanation-1: -Unlike active immunity, passive immunity provides immediate protection. But that protection is generally short-lived, as the supply of antibodies is not being replenished like they would be in someone whose own immune system was generating them.

Detailed explanation-2: -The major advantage to passive immunity is that protection is immediate, whereas active immunity takes time (usually several weeks) to develop. However, passive immunity lasts only for a few weeks or months. Only active immunity is long-lasting.

Detailed explanation-3: -In many cases, acquired immunity is lifelong, as with measles or rubella. In other instances, it can be short-lived, lasting not more than a few months. The persistence of acquired immunity is related not only to the level of circulating antibody but also to sensitized T cells (cell-mediated immunity).

Detailed explanation-4: -Viruses pose a challenge to the body’s immune system because they hide inside cells. It is possible to be vaccinated against some of the major disease-causing viruses (such as measles and polio), as well as bacterial diseases such as Hemophilus influenza Type b (Hib), tetanus and whooping cough.