Same Scar On Many People Is Sparking Confusion Online, But Here’s Why So Many Have It

Apart from trends, there are many new things that netizens learn on social media. I mean, ever since the digital revolution, information is readily available at the tip of everyone’s fingertips. Recently, something unusual has been quizzing folks on X, and surprisingly it’s about the same scar.

This small, circular mark is found on many people, but some had absolutely no clue about its origins. It sparked confusion online, but they were finally able to understand the real reason behind the scar. If it has baffled you as well, just scroll down to read all about it!

Netizens noticed an unusual scar that many people have and got confused about its origins

National Cancer Institute / Unsplash (not the actual photo)

Just last month, X users were tweeting about how many people have this unusual little scar that almost looks like a bite mark. It resides at the top of the arms, has a recognizable center, and has small ridges on the skin.

Folks who have it might know where it came from. Others had no idea that it’s from a Bacille Calmette-Guérin BCG vaccine or smallpox vaccine. The BCG vaccine protects from tuberculosis.

However, in 1980, WHO declared smallpox eradicated, the only infectious disease to achieve this distinction. Also, smallpox vaccination was halted between 1971-72 in the UK and the US, so only people born before then have the scar.

Bacille Calmette-Guérin BCG vaccines (that protect against TB) and smallpox vaccines generally leave these scars

pianoman81 / Reddit

Research shows that a total of 1.23 million people were lost to tuberculosis in 2024. Globally, TB is the world’s leading cause of fatalities from a single infectious agent. Meanwhile, the BCG vaccine, first introduced in 1921, remains the only vaccine used to prevent TB. 

According to the updated BCG World Atlas, about 150 countries still have BCG vaccination programs for children and infants. These include countries such as India, China, South Africa, Kenya, Russia, Vietnam, Brazil, Thailand, etc., where TB is more commonly found than in other nations. 

However, TB in the US is uncommon. The Centers for Disease Control and Prevention (CDC) states that in 2025, 10,260 TB cases were provisionally reported, corresponding to a rate of 3.0 cases per 100,000 population. This represented a 1% decrease in cases and a 2% decrease in rates from 2024 to 2025. 

Getty Images / Unsplash (not the actual photo)

TB is uncommon in the US, but people can still take the BCG jab if they meet the criteria

Despite the numbers, people in America can get the BCG vaccine if they meet “specific criteria” and “consult a TB expert.” The scar is just a side effect of the jab. The NHS points out that it’s the main side effect, causing a blister at the jab site.

“This may appear as a raised bubble straight after the injection and then turn into a blister or a sore after 2 weeks. It then forms a scab and can take a few weeks or months to heal, leaving a small flat scar,” it adds.

Apart from that, there are mild side effects such as fever, headache, and swollen glands under the armpit on the side where the vaccine was given. However, these are pretty rare.

CDC / Unsplash (not the actual photo)

As for smallpox, the jab causes a minor infection in the skin that leaves a scar. “Your body fights off the infection, but this process leaves behind a small mark on your skin where the infection took place. This scar is a sign that the vaccine worked. It gave you immunity against smallpox, as it’s designed to do,” highlight the experts at Cleveland Clinic.

But as we mentioned before, the injections were stopped when smallpox was eradicated. Today, only military and lab workers might get this vaccine. 

Netizens have noticed that many celebrities also have these scars, and they have gone viral as “immigrant scars.” This colloquial term clearly indicates that someone is an immigrant, as not all countries give the BCG vaccine.

What about you? Do you have this unusual scar, and were you aware of the reason why so many do? Let us know your thoughts in the comments!

Netizens who were unaware of the scar were surprised to know how it came to be

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