Question

The active immunity offered by tetanus toxoid is effectively present in nearly:

• A. 25 percent of the patients
• B. 50 percent of the patients
• C. 75 percent of the patients
• D. 100 percent of the patients

Hint:

A full primary course of tetanus toxoid protects nearly all recipients, about 80 to 100 percent.

Answer 1

The Correct Option is D

Step 1: Understand the vaccine.
Tetanus toxoid is the inactivated, toxoid form of the tetanus exotoxin, given to make the body build its own protective antibodies. This is active immunity, different from giving ready made antibodies, which would be passive immunity.

Step 2: Attach a number to "effective".
Public health teaching describes a completed primary schedule of tetanus toxoid as protective in almost every healthy person who receives it, generally placed at about 80 to 100 percent seroconversion. In simple exam language, this is rounded to nearly 100 percent.

Step 3: Weigh the choices against this number.
A quarter or half of patients being protected, 25 percent or 50 percent, would make tetanus toxoid a weak vaccine, which does not match its real world record as a dependable, widely used immunization. Three quarters, 75 percent, sits near the bottom of the reported range, so it undercounts the protection most people actually get. The option of nearly all patients being protected fits best with how the vaccine performs after a full course.

Step 4: Acknowledge the close call.
The source answer sheet itself flags that both 75 percent and 100 percent could be defended, since the quoted range spans 80 to 100 percent. Sticking with the stated key and the general teaching that tetanus toxoid protection is close to universal after a complete course, the best single choice is nearly 100 percent.
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