The History Behind the Smallpox Vaccine Scar

Smallpox was a contagious disease caused by the variola virus. The typical symptoms of smallpox include a skin rash, back pain, headache, fatigue, and high fever. Around 30% of people who contracted smallpox died. 

Due to the success of the smallpox vaccine in the 1960s and 1970s, smallpox was eradicated in 1980. Now, the smallpox vaccine is only given to certain groups, such as certain military service members and laboratory workers.

Some people who have had the smallpox vaccine may have a permanent scar on their upper arm in the area where they received the injection. Learn more about why the smallpox vaccine often left behind a scar.

Smallpox vaccine

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Smallpox Vaccination: Does Everyone Have a Scar?

The smallpox vaccine usually left behind a distinctive round scar on the upper arm during the healing process. Having a scar is typically a sign that the vaccine was successful or that it “took.” The scar was more obvious after the first smallpox vaccine than after revaccination for people who needed boosters.

Reasons Why Scarring Happened

The smallpox vaccine, ACAM2000, is a live vaccine. It contains a live version of vaccinia, a virus similar to smallpox but not as dangerous. Routine vaccination against smallpox has ended because the virus has been destroyed worldwide, but U.S. government agencies still have access to the vaccine in case of another smallpox outbreak. 

After being vaccinated against smallpox, most people developed an itchy, painful, and red skin lesion within three to four days. In the following two to three weeks, the lesion would become a pus-filled blister, drain, and scab over before forming a round scar where they received the vaccine.

A healthcare provider would sometimes check to see if the scar had formed in about six to eight days. This was a good sign that the vaccine had been successful. If no sore formed, revaccination was sometimes recommended.

The smallpox vaccine was administered with the unique “multiple puncture” technique rather than as a shot. To deliver the vaccine, a healthcare provider would dip a two-pronged needle into the vaccine solution and prick the skin multiple times. This technique caused the skin to react as it healed.

Can the Smallpox Vaccine Cause Smallpox?

You can’t get or spread smallpox from the smallpox vaccine. However, people who received the vaccine could spread the vaccinia virus to people who came into contact with their skin lesion before it healed. Keeping the vaccination site covered reduced the risk of spreading vaccinia.

What Made the Smallpox Vaccine Needle Different

The smallpox vaccine was delivered using a bifurcated, or two-pronged, needle. This means that it had two sharp points instead of one. Healthcare providers would place a single drop of the smallpox vaccine solution between the two prongs before holding the needle perpendicular to a patient’s skin and pricking an area of the upper arm several times in a matter of seconds. This process wasn’t very painful, but it usually caused a trace of blood to appear shortly after vaccination.

When Was the Last Smallpox Outbreak?

In the United States, the last outbreak of smallpox occurred in 1949. The last known case of smallpox worldwide occurred in 1977 in Somalia, after which the disease was declared eradicated.

Smallpox vs. BCG Vaccine Scar

Like the smallpox vaccine, the Bacille Calmette-Guérin (BCG) vaccine,which offers protection against tuberculosis (TB) disease, is not given routinely in the United States. It’s still often administered to infants and children in countries where TB disease is more common. 

Both the smallpox vaccine and the tuberculosis vaccine cause a blister to fill with pus, crust over, and form a scab within a few weeks. People who received the BCG vaccine in the past often have a permanent scar in the area where they received the injection. 

However, the BCG vaccine scar is typically raised in the middle and may have more rounded edges. The smallpox vaccine is usually depressed, or lower than the skin around it. The edges of the scar may be more irregular.

Smallpox Vaccine for Mpox

In 2019, the Food and Drug Administration (FDA) approved the use of the JYNNEOS vaccine to protect against both smallpox and mpox, once referred to as monkeypox. The mpox virus is similar to smallpox, but the symptoms of mpox are typically less severe and not often fatal. 

Some people are concerned that smallpox/mpox vaccine may lead to a permanent scar. However, unlike the smallpox vaccine, JYNNEOS doesn’t cause skin lesions or scarring. Common side effects of smallpox/mpox vaccine include:

  • Temporary itching, pain, or redness at the injection site
  • Fatigue
  • Muscle pain
  • Headache

The smallpox/mpox vaccine is delivered in a two-dose series. If you previously had the smallpox vaccine (ACAM2000), your healthcare provider may recommend that you get only one dose. Talk to your healthcare provider about getting vaccinated if you think you may be at risk for the mpox virus.

Remedies to Heal Vaccine Scars

Talk to a dermatologist if you’re interested in reducing the appearance of your vaccine scar. Possible treatments include:

  • Steroid injections
  • Dermal fillers
  • Subcision, which involves placing small needles under the skin
  • Laser resurfacing

Using sunscreen and moisturizer on your scar can help to protect that area of your skin, which may be more sensitive. Your dermatologist might also recommend a scar cream to make your scar less noticeable.


Smallpox, a serious disease caused by the variola virus, typically leads to symptoms like high-grade fever and a skin rash. Thanks to the success of a worldwide immunization program, smallpox was eradicated in 1980. However, people who received the smallpox vaccine may still have a scar on their upper arm.

The smallpox vaccine was administered using a bifurcated needle and multiple puncture technique. This caused a skin lesion, typically turning into a pus-filled blister and scabbing within a few weeks. For most people, this turned into a permanent depressed scar. The smallpox/mpox vaccine, JYNNEOS, does not lead to scarring.

Frequently Asked Questions

  • What year was the last dose of the smallpox vaccine given?

    In the United States, routine smallpox vaccination ended in 1972. Since then, the smallpox vaccine has not been available to the public. It has only been given to small groups of scientists, researchers, laboratory workers, and military service members who may be at risk of exposure.

  • Do other vaccines leave scars?

    Bacille Calmette-Guérin (BCG), which protects against tuberculosis (TB), also leaves behind a scar during the healing process. The tuberculosis vaccine is no longer widely available in the United States. However, many people born outside the United States continue to receive BCG vaccines just after birth.

  • What shape is a smallpox vaccine scar?

    A smallpox vaccine scar usually appears round- or oval-shaped. It’s typically about the size of a dime. It may look “deeper” or lower than the surrounding skin.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Laura Dorwart
Laura Dorwart is a health journalist with particular interests in mental health, pregnancy-related conditions, and disability rights. She has published work in VICE, SELF, The New York Times, The Guardian, The Week, HuffPost, BuzzFeed Reader, Catapult, Pacific Standard,, Insider,, TalkPoverty, and many other outlets.