Why do many people have a small scar on their left arm?

Unlike current vaccines, the smallpox vaccine was administered using a unique technique using a bifurcated needle. The needle, with two small points, repeatedly pierced the skin to introduce a small amount of the virus into the dermis. This method created a characteristic skin reaction: a blister formed at the injection site, which eventually burst, leaving behind a scab and then a circular scar. “This scar is a testament to a time when medicine was fighting diseases that would otherwise be deadly,” says Lydia Mammar, a medical historian.
Smallpox vaccination was almost always given on the upper left arm to make it easier to monitor the reaction to the vaccine without interfering with the patient’s daily activities. This scar has become a common sign, especially among people born before the 1970s, when mass vaccination campaigns against smallpox ended.

A Mark of Protection

The next time you see that little scar, remember that it is more than just a mark on your skin. It is the visible sign of a fight against a once-terrible disease that has now been eradicated. This little mark is a reflection of a medical battle and a collective success for public health, a reminder of the power of vaccines and advances in disease prevention.

In short, this scar is more than just an imperfection; it is the symbol of a historic medical victory.