5 common misconceptions about the round scar on the upper arm

Not everyone who receives the BCG vaccine develops a visible scar. In some people, the scar heals with little to no trace. In others, the scar fades significantly over time.

The absence of a scar does not automatically mean that a person has never been vaccinated, just as the presence of a scar does not indicate stronger or weaker immunity.

Smallpox vaccination scar: Pictures, causes, and more

Myth #4: “The scar means your immune system is weak or damaged.”

Another fear is that the scar indicates long-term damage to the immune system or a persistent susceptibility to disease.