People who grew up in Asia, Africa, Latin America, or parts of Eastern Europe are more likely to have a small, round scar on their upper arm. It’s about the size of an eraser, slightly indented, and perhaps a little lighter than the surrounding skin.

For years, maybe you hadn’t thought twice about it. But then someone asked you. Or you noticed it in a photo. Or you wondered:    where did it come from?

Some make up explanations. Others are ashamed and assume it’s a childhood accident they’ve forgotten. But the truth is simpler and more universal than you might think.

This little scar has generated confusion for decades. Let’s clear things up.

Common misconceptions about round arm scars

Myth #1: “This is from a vaccine I received as a child.”

The truth is that    this statement is indeed    correct   , but only for certain generations and regions.

The round scar on my upper arm is actually the result of a vaccination. More specifically, it’s the scar      left by the  BCG (Bacillus Calmette-Guérin) vaccine, which protects against tuberculosis (TB).

  • Who is affected:    Children born before the mid-2000s in many countries, especially in Asia, Africa, Latin America, and Eastern Europe.

  • Why a scar formed:    The BCG vaccine was administered intradermally (into the skin) rather than intramuscularly. This method intentionally creates a local reaction that leads to the formation of a pustule, which subsequently heals, leaving a scar, demonstrating the effectiveness of the vaccination.

    Anatomy

  • Why some countries have stopped vaccinations:    In some regions, as tuberculosis rates have declined, routine BCG vaccination has been replaced by targeted vaccinations for at-risk groups. In other regions, improved vaccine formulations have reduced scarring.

If you have this scar, it means you were protected from one of the deadliest diseases in history.    There’s nothing to hide. You should be grateful.