What type of vaccine is the BCG vaccine?

UPRVUNL - 2021

Applied Microbiology & Infection control

Easy

Appeared in: UPRVUNL - 2021

Explanation

The BCG (Bacillus Calmette-Guérin) vaccine is prepared from a live, but weakened (attenuated), strain of Mycobacterium bovis.
Live attenuated vaccines work by mimicking a natural infection, which stimulates a robust and long-lasting immune response.
This type of vaccine induces both humoral (antibody-mediated) and cellular immunity, which is critical for protection against intracellular pathogens like the tuberculosis bacterium.
Other examples of live attenuated vaccines include those for measles, mumps, rubella (MMR), and oral polio (OPV).

Option B: A 'triple vaccine' is a type of combination vaccine that protects against three different diseases, such as the MMR (Measles, Mumps, Rubella) vaccine. BCG only protects against one disease: tuberculosis.
Option C: A killed (inactivated) vaccine contains microorganisms that have been killed and can no longer replicate. The BCG vaccine contains live, albeit weakened, bacteria.
Option D: A 'combined vaccine' contains antigens for multiple diseases in a single injection to reduce the number of shots needed. While this is a valid vaccine category, BCG is a single-antigen vaccine protecting only against tuberculosis. Therefore, 'live attenuated' is a more precise and accurate classification of the BCG vaccine's nature.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of Vaccines as background academic context rather than a clinical decision trigger.
Nurses must know the type of vaccine they are administering because it has implications for storage, handling, and patient contraindications. For example, live vaccines like BCG are generally contraindicated in immunocompromised individuals (e.g., those with HIV/AIDS or on chemotherapy) and pregnant women due to the risk of the weakened pathogen causing disease.
Proper administration technique is critical. BCG must be given intradermally to ensure a proper immune response and avoid complications like local abscesses or lymphadenitis, which are more common with subcutaneous injection.
Patient education is a key nursing role. The nurse must explain the expected reaction at the injection site (a small papule that evolves into a scar) and when to seek medical advice for adverse reactions.

How to Approach the Question

First, identify the core of the question, which is to classify the BCG vaccine.
Recall or look up the definition of a BCG vaccine. The name itself, Bacillus Calmette-Guérin, refers to a live bacterium.
Analyze the given options: 'Live attenuated', 'Triple', 'Killed', and 'Combined'.
Evaluate each option against the properties of the BCG vaccine.
BCG uses a weakened live organism, which matches the definition of a 'Live attenuated vaccine'.
Eliminate the other options. 'Killed' is the opposite. 'Triple' and 'Combined' refer to the number of diseases protected against, and BCG only targets one (tuberculosis).

Concept Tested & Keywords

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