Passive natural immunity occurs via:

Passive natural immunity occurs via:

• A. Infection
• B. Mother to infant
• C. Vaccination
• D. Injection of immune serum

Answer: (B)

Passive natural immunity is the transfer of antibodies from one individual to another, giving immediate protection without the recipient having to produce antibodies themselves. The newborn receives this protection from the mother through the placenta during pregnancy (IgG) and after birth through breast milk (primarily secretory IgA). This kind of immunity acts right away but is temporary because the antibodies are not made by the infant’s own immune system and eventually wane. This is why the option describing transfer from mother to infant is the best choice. Infections and vaccines rely on the person’s own immune system to respond and generate antibodies—infection creates active immunity through exposure to pathogens, while vaccination exposes the immune system to antigens to produce a protective response (also active). Receiving immune serum, though it provides antibodies, is a passive form of immunity that is artificial rather than natural.

Passive natural immunity is the transfer of antibodies from one individual to another, giving immediate protection without the recipient having to produce antibodies themselves. The newborn receives this protection from the mother through the placenta during pregnancy (IgG) and after birth through breast milk (primarily secretory IgA). This kind of immunity acts right away but is temporary because the antibodies are not made by the infant’s own immune system and eventually wane.

This is why the option describing transfer from mother to infant is the best choice. Infections and vaccines rely on the person’s own immune system to respond and generate antibodies—infection creates active immunity through exposure to pathogens, while vaccination exposes the immune system to antigens to produce a protective response (also active). Receiving immune serum, though it provides antibodies, is a passive form of immunity that is artificial rather than natural.