As a child, I distinctly remember noticing a scar on my mother’s arm.

It was positioned high on her upper arm, near her shoulder, with a unique pattern that resembled a ring of small indentations

surrounding a larger one. For some reason, it caught my attention, though I can’t recall exactly why.

I remember being curious about it, but over time, as many childhood memories do, that curiosity faded, and the scar was no longer a focus in my mind.

Of course, I didn’t forget that the scar was still there, but I did forget that I had once been so intrigued by it. Maybe I had asked my mother about it at some point, and if she explained it, I must have not found it important enough to retain. The mystery of the scar lingered in the back of my mind, yet it wasn’t something I thought about for years.

Then, one summer a few years ago, an unexpected event triggered my curiosity again. I was helping an elderly woman off a train,

and as she turned her arm, I noticed an identical scar in the same spot, high on her arm, just like my mother’s.

My curiosity immediately resurfaced, and I wished I had the chance to ask her about it. Unfortunately, with the train soon leaving the station, I didn’t have the time to inquire.

Instead, I called my mother later that day, eager to finally get the answer to the mystery. She laughed and reminded me that she had explained it to me more than once before,

though clearly, my memory had failed me. The scar, she told me, came from the smallpox vaccine.

Smallpox was a dangerous viral disease that once had a significant impact on the global population. It caused severe rashes, high fever, and, in many cases, death. According to the Centers for Disease Control and Prevention, approximately 30% of those infected with smallpox died, and many others were left with disfiguring scars. Thanks to a successful global vaccination campaign, smallpox was eradicated in the United States in 1952, and routine vaccinations ceased in 1972.

Before the disease was eliminated, smallpox vaccinations were part of the standard inoculation schedule for all children. This vaccine left behind a distinctive scar, and it became a symbol of successful vaccination. It was almost like a “vaccine passport,” a permanent mark that indicated an individual had been vaccinated. This scar, which my mother carries, was a common sight for people in her generation, as almost everyone who was vaccinated at the time developed this distinctive mark.

So why did the smallpox vaccine cause such a visible scar?

The answer lies in the way the vaccine was administered. Unlike modern vaccines, which are typically given through a single needle injection, the smallpox vaccine was delivered using a special two-pronged needle. The person administering the vaccine would make several punctures in the skin, which was quite different from the single puncture used in other vaccinations. The vaccine was delivered into the skin’s dermis layer, which is located just beneath the surface.

Once administered, the virus in the vaccine began to work within the body. It multiplied, causing the skin to react by forming round bumps. These bumps eventually turned into vesicles, small fluid-filled blisters. Over time, these blisters would burst and form scabs, which would eventually fall off, leaving behind the characteristic scar.

This scar, often located on the upper arm, became the trademark of a successful smallpox vaccination. It was not just a reminder of the body’s immune response but also a sign that the individual had been protected from one of history’s most feared diseases.

While the smallpox vaccine is no longer a part of routine vaccinations today, the scars it left behind remain as a testament to the disease’s eradication.

The end of smallpox vaccination marked a significant milestone in public health, and those who bear the scars of the vaccine are a reminder of the global effort that led to the disease’s extinction. For my mother, and many others from her generation, the scar is both a physical mark and a historical one, representing a time when the world came together to conquer a deadly disease.