NORCET 9 Mains - 2025: After BCG vaccine administration, after how many weeks should the vaccine site be checked for ‘take’ response…

NORCET 9 Mains - 2025

Child Health Nursing (Pediatrics)

Easy

Appeared in: NORCET 9 Mains - 2025

Explanation

The 'take' response for a BCG vaccine refers to the development of a local reaction and tuberculin hypersensitivity, indicating a successful immune response.
This immune response, demonstrated by becoming Mantoux-positive, typically occurs by 8 weeks post-vaccination.
The local skin reaction, which involves the formation of a papule that evolves into an ulcer and then a scar, is also at its peak or beginning to heal during the 6-8 week period.
This timeframe often aligns with an infant's next immunization visit (e.g., for DPT-1), making it a practical point for assessment.

Option B: While a significant local reaction (ulceration) is present at 4–6 weeks, it is still developing. Checking at this time may be too early to definitively confirm the development of tuberculin sensitivity.
Option C: At 3–4 weeks, the reaction is in its early stages, typically just a papule. It is too soon to assess for a successful 'take'.
Option D: This is the very beginning of the local reaction, when the initial papule first appears. It is far too early to determine if the vaccination has been successful.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Post-vaccination assessment and timeline for BCG vaccine efficacy as background academic context rather than a clinical decision trigger.
Nurses must educate parents about the expected BCG reaction, reassuring them that the papule and ulcer are normal signs of the vaccine working and should not be squeezed or covered.
Proper assessment of the BCG 'take' is crucial. The absence of a scar by 3 months may indicate vaccine failure, requiring a follow-up Mantoux test to check for immunity and potential revaccination.
What if? If a child at 8 weeks shows no local reaction at all (no papule or ulcer ever formed), it suggests primary vaccine failure. The nurse should document this and refer the child for a Tuberculin Skin Test (TST) after 12 weeks to assess immunity before considering revaccination.

How to Approach the Question

First, identify the core of the question: it asks for the specific timing to check the 'take' response of a BCG vaccine.
Recall the purpose of the 'take' response. It's not just the visible skin lesion but the underlying immune conversion (tuberculin sensitivity).
Mentally review the timeline of the BCG skin reaction: papule (2-3 weeks) -> ulcer (4-6 weeks) -> healing/scarring (6-12 weeks).
Correlate this with the development of immunity. Tuberculin sensitivity is the key indicator and is established around 8 weeks.
Evaluate the options against this timeline. The 6-8 week window is the only one that correctly captures the period when both the local reaction is peaking and immunity is established.
Eliminate other options as being too early in the reaction process to confirm a successful vaccination.

Concept Tested & Keywords

Concept Tested: Post-vaccination assessment and timeline for BCG vaccine efficacy.
Stem keywords: BCG vaccine, vaccine site, take response
Lead-in keywords: after how many weeks

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