BCG vaccine is diluted in?

Appeared in: IGNOU Post B. SC. Nursing entrance -2021

Explanation

The BCG vaccine is a live attenuated (weakened) vaccine that comes in a freeze-dried powder form.
It must be reconstituted with Normal Saline (0.9% NaCl) before administration.
Normal saline is an isotonic solution, which means it has the same salt concentration as body fluids. This prevents damage to the live bacterial cells in the vaccine and minimizes irritation at the injection site.
Using any other diluent can inactivate the vaccine or cause adverse local reactions.

Option A: Distilled water is hypotonic. It would cause the live bacterial cells in the BCG vaccine to swell and burst, making the vaccine ineffective. It can also cause severe local irritation.
Option C: Dextrose solutions contain sugar, which can alter the pH and stability of the vaccine, potentially reducing its effectiveness.
Option D: Ringer's lactate contains electrolytes like potassium and calcium that are not compatible with the BCG vaccine formulation and can interfere with its stability.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Vaccine reconstitution and diluents as background academic context rather than a clinical decision trigger.
The 'Reconstitution Rule' is a critical patient safety principle: always use the specific diluent provided by the manufacturer or as per official guidelines. Interchanging diluents can inactivate the vaccine or cause adverse reactions.
Once reconstituted, the BCG vaccine is highly unstable. It must be protected from light, kept cool (between +2°C and +8°C), and used within 4-6 hours. Any unused vaccine must be discarded to prevent contamination and loss of potency.
What if? If the BCG vaccine is accidentally reconstituted with distilled water, it must be discarded immediately. The patient should not be vaccinated with this mixture. A new vial must be correctly reconstituted with normal saline for administration.

How to Approach the Question

First, identify the core of the question, which is about the specific diluent for the BCG vaccine.
This is a factual recall question common in pharmacology and community health nursing.
Recall the principles of vaccine reconstitution. Live vaccines are particularly sensitive to the type of diluent used.
Differentiate between the diluents for common vaccines. Remember that BCG uses normal saline, while measles uses distilled water. This is a frequent point of confusion and a common exam topic.
Select the option that matches the standard protocol for BCG.

Concept Tested & Keywords

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart B (pp 202-403 of 604) p. 42-44

E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 68-70

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