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 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.

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.

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.

Summary

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.