A 2-week-old neonate born at a government hospital in rural India received routine immunization at birth as per the UIP schedule. The vaccine marked **A** in the diagram was administered by intradermal injection over the left deltoid. Two weeks later, the mother notices a small ulceration at the injection site with mild local swelling. She is concerned this represents an infection or adverse reaction. Which of the following best explains this clinical finding?

Question

Accepted Answer

A. This is an expected local reaction to BCG vaccination; the ulceration and subsequent scar formation are normal and indicate successful take of the vaccine. The vaccine marked **A** is BCG (Bacille Calmette-Guérin), a live attenuated M. bovis vaccine given at birth by intradermal injection (0.05 mL in neonates <1 month) over the left deltoid. A small papule that ulcerates over 2–4 weeks and then heals, leaving a permanent scar, is the NORMAL expected local reaction to BCG vaccination. This scar is used as clinical evidence of past vaccination and does NOT indicate infection or adverse reaction. The mother's observation of mild ulceration with local swelling at 2 weeks is entirely consistent with the natural course of BCG take and requires no intervention. This distinguishes normal BCG take from true adverse events like regional lymphadenitis (>3 cm suppurative nodes requiring aspiration) or disseminated BCG-osis (rare, in severely immunocompromised infants). [Park 26e Ch 8; UIP/IAP guidelines 2024]

Answer

B. This represents regional lymphadenitis, a serious adverse event requiring immediate needle aspiration and anti-tuberculous therapy

Answer

C. This is evidence of disseminated BCG-osis and the infant requires urgent systemic anti-TB treatment including pyrazinamide

Answer

D. This indicates vaccine failure and the infant should be revaccinated with a second dose of BCG as per current WHO guidelines

Explanation

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