Misconception #2: “It’s a smallpox vaccine scar.”
The truth: This is the most common confusion—and it’s easy to understand why.
The smallpox vaccine also leaves a round scar, typically on the upper arm. But there are key differences:
Feature BCG Scar (Tuberculosis) Smallpox Scar
Size Smaller (about 5-8mm) Larger (about 10-15mm)
Appearance Usually round, slightly indented Often more textured, may have a “dimpled” center
Timing Given in infancy (in many countries) Given later in childhood (in countries that used it)
Current use Still used in many countries Discontinued worldwide after 1980
Smallpox vaccination ended globally in 1980 after the disease was declared eradicated. If you were born after 1980, your scar is almost certainly from BCG.
If you’re older and have a larger, more textured scar, it might be from smallpox. But for most people reading this, it’s BCG.
Misconception #3: “It’s from a bad reaction to a regular shot.”
The truth: The BCG vaccine is unique in how it’s given.
Most vaccines are injected into muscle (intramuscular) or just under the skin (subcutaneous). These methods are designed to minimize tissue reaction and scarring.
