administered on the upper arm.
For people vaccinated during mass smallpox vaccination campaigns, the resulting scar could remain visible for decades.
Over time, the mark became almost like a historical signature—something that could tell you that a person had received an older type of vaccine.
Smallpox Was Once a Major Threat
Today, it can be difficult to imagine how dangerous smallpox once was.
The disease caused enormous suffering and death around the world for centuries.
The development and widespread use of vaccination eventually transformed the situation.
In 1980, the World Health Organization officially declared smallpox eradicated, making it the first human disease to be eradicated through deliberate public-health efforts.
That makes the little scar on someone’s arm more than just an unusual physical mark.
For many people, it represents a moment in medical history.
Is It a Smallpox Scar or a BCG Scar?
This is where things can become confusing.
