Question

Which one of the following doses, in lethal flocculating units of Diphtheria Toxoid, is incorporated in DPT vaccine?

• A. 5
• B. 15
• C. 25
• D. 35

Hint:

Recall the standard Lf content fixed for diphtheria toxoid in DPT vaccine.

Answer 1

The Correct Option is C

This question is a straight recall question about how much diphtheria toxoid goes into the DPT vaccine, measured in Lf units.

1. 5: This figure is far too small to match the standard content used for diphtheria toxoid in DPT.
2. 15: This is still below the accepted standard dose for the diphtheria component.
3. 25: This is the fixed standard content of diphtheria toxoid built into every dose of DPT vaccine, set by manufacturing and quality control standards.
4. 35: This figure goes above the standard content and is not what is actually used.

Vaccine components are standardised so that each dose delivers enough antigen for a good immune response without causing excess local reaction, and for diphtheria toxoid in DPT that fixed figure is 25 Lf.

So the correct dose of diphtheria toxoid incorporated in DPT vaccine is 25 lethal flocculating units.