BCG vaccine is an example of?

Appeared in: MNS 2024

Explanation

BCG (Bacillus Calmette-Guérin) is a live vaccine prepared from an attenuated (weakened) strain of Mycobacterium bovis.
Live-attenuated vaccines contain living organisms that multiply in the host, mimicking a natural infection without causing the disease.
This process stimulates a robust and long-lasting immune response, particularly cell-mediated immunity, which is crucial for protection against tuberculosis.
The World Health Organization (WHO) recommends the 'Danish 1331' strain for BCG vaccine production.

Option B: Killed vaccines contain pathogens that are completely inactivated (killed) and cannot replicate. BCG contains live, albeit weakened, bacteria.
Option C: Toxoids are vaccines made from inactivated bacterial toxins, not the bacteria themselves. BCG is made from the whole bacterium.
Option D: Subunit vaccines use only specific parts (antigens) of the pathogen, not the entire organism. BCG uses the whole, live organism.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of vaccines based on their composition and mechanism as background academic context rather than a clinical decision trigger.
A key nursing responsibility is correct administration. BCG must be given intradermally on the left deltoid. Subcutaneous injection can lead to abscess formation.
Patient education is vital. Nurses must inform parents about the normal evolution of the BCG site reaction (papule to ulcer to scar) to prevent unnecessary anxiety and improper care of the site.
Screening for contraindications is a critical safety measure. Nurses must assess for signs of immunodeficiency in newborns before administering BCG to prevent the life-threatening complication of disseminated BCG infection.

How to Approach the Question

First, identify the core subject of the question, which is 'BCG vaccine'.
This is a factual recall question that tests your knowledge of immunology and common vaccines.
Recall the composition of the BCG vaccine. You should remember it's a live vaccine used for tuberculosis prevention.
Scan the options to find the category that matches 'live vaccine'. 'Live-attenuated vaccine' is the precise term.
Mentally confirm that the other options (Killed, Toxoid, Subunit) represent different mechanisms and do not apply to BCG.

Concept Tested & Keywords

Concept Tested: Classification of vaccines based on their composition and mechanism.
Stem keywords: BCG vaccine
Lead-in keywords: example of
Negative lead-in flag: false

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart B (pp 202-403 of 604) p. 41-43

E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) p. 96-98

E6 Microbiology Essentials Sastry 4e Part 1 p. 99-101

Practise the full MNS 2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.