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: Recall what tetanus toxoid does.
Tetanus toxoid is a vaccine made from the inactivated toxin of Clostridium tetani. When given as a full primary course, it trains the immune system to make protective antibodies, giving active immunity against tetanus.

Step 2: Recall how effective this immunity is.
A completed primary series of tetanus toxoid produces protective antibody levels in almost all healthy recipients, commonly quoted in the range of about 80 to 100 percent, described in practice as nearly 100 percent protection. This is one reason tetanus toxoid is seen as one of the most reliable vaccines used in public health programs.

Step 3: Compare the given options.
25 percent and 50 percent are far too low for a vaccine relied upon worldwide to prevent tetanus after a completed schedule. 75 percent sits near the lower end of the quoted range but undersells how consistently protective a full course is. 100 percent, read as nearly 100 percent since no vaccine gives an absolute, un-exceeded guarantee, best matches standard teaching.

Step 4: Note on the source answer key.
The original answer key marks option 4 as correct but also notes the true range is about 80 to 100 percent, treating option 3, 75 percent, as an acceptable near miss. Following the stated best answer and current teaching that a completed tetanus toxoid course protects nearly all recipients, option 4 is kept as the answer here.

Step 5: Final Answer.
Tetanus toxoid gives active immunity in nearly 100 percent of patients who complete the primary series.
\[ \boxed{100\%} \]