Question

If a person is infected with a deadly pathogen/toxin against which quick immune response is required, ready-made antibodies are directly given to protect that person based on the principle of passive immunity. Select the option that does not represent a case of passive immunity.
A. Administration of antivenom against snake bite
B. Administration of anti-tetanus serum
C. Administration of tetanus toxoid to newly born
D. Passage of LgG across placenta from mother to foetus.

Answer 1

Passive immunity gives instant safety against infection, but that protection is temporary. The antibodies will decrease during a period of weeks to months, and the receiver will no longer be saved.

Complete Answer:
To answer this question, first, we need to know about passive immunity. Passive immunity is given when a person is provided antibodies to a disease rather than making them via her or his own immunity system. An infant or newly born baby gets passive immunity from its mother via the placenta or breast milk.
Now, let us find the solution from the option.
In the case of administration of antivenom against snake bite or anti-tetanus serum the doses contain antibodies which go and attack their target antigens in the body.
The administration of the tetanus toxoid triggers the body to generate protective antibodies against the toxins.
In the instance of tetanus toxoid, when administered in a newborn, the vaccine contains detoxified tetanus toxins (which does not lose their immunogenic properties).

The passage of IgG across the placenta also helps the fetus to fight infections directly.

Thus, the correct option is C. i.e. Administration of tetanus toxoid to newly born.

Note: Immunity that develops after a person receives immune system components, most commonly antibodies, from another person. Passive immunity can get naturally like when an infant gets a mother's antibodies via the placenta or breast milk, or artificially, like when a person gets antibodies by the injection. Passive immunity gives instant safeguard against an antigen, but it is not effective for a longer period of time.