Many Kenyans bear a small, round scar on their upper arm from childhood, a lasting mark left by the Bacille Calmette-Guérin (BCG) vaccine administered to protect against tuberculosis (TB).

• The scar is a normal local reaction to the intradermal injection of the BCG vaccine, not an indication of error.
• The World Health Organisation (WHO) recommends a single BCG dose for infants in high TB burden areas.
• While the scar suggests vaccination, its absence does not mean the vaccine failed or that protection was not received.