What is this scar on your hand? Let's learn about the Smallpox Vaccine Scar!

Do you have a small, round, perhaps slightly sunken scar on your arm, just below the shoulder? You may have seen this scar on your mother, father, or grandparents' hands. Many people think it's just an old scar. But there's actually a big story behind it. Today, let's talk about this smallpox vaccine scar.

What exactly is a smallpox vaccine scar?

Simply put, this is proof that you have been vaccinated against smallpox. This rash is usually round, but sometimes the edges can be slightly raised. It can also be slightly sunken and lower than the surrounding skin.

There are two main types of vaccines that cause this scar:

• ACAM2000™: This is the vaccine currently used to protect against smallpox. However, it is not given to everyone. Because smallpox has been eradicated from the world thanks to vaccination programs launched under the leadership of the World Health Organization, it is now only given to special groups, such as laboratory workers who work with certain types of viruses and military personnel in some countries.
• Dryvax®: This is the vaccine used before the ACAM2000 vaccine. This vaccine was given to millions of people in many countries around the world, including Sri Lanka, in the mid-1900s. The vaccine was discontinued for the general public in 1972. After that, it was only given to essential people, such as health workers.

This means that if you have this scar on your hand, you probably received the Dryvax® vaccine decades ago.

Why does this vaccine cause such a scar?

The reason for this is interesting. The smallpox vaccine leaves a scar because the vaccine intentionally creates a small, controlled infection in your skin. Your body's immune system fights this infection and defeats it. That's where that "fight" took place, and that's where this small scar is left.

Here's how this happens:

When the doctor gives the injection, he uses a special needle with a bifurcated tip. This needle is dipped in the injection fluid and pricked several times on the skin of your upper arm.

This method causes a small infection to develop at that site. There's nothing to worry about, this is what's supposed to happen. This infection "trains" your immune system, preparing it to fight the real smallpox virus if it comes along.

Within 3-4 days of getting the vaccine, the area will become red, slightly swollen, and itchy. This is called "a take." It means the vaccine is working properly.

• After a few days, this red spot turns into a pus-filled blister.
• After about 10 days, this will start to dry out a little.
• Next, a crust forms in that place.
• This scab will fall off in 14-21 days, leaving behind a small, sunken scar.

This scar is a good sign that your body has successfully built immunity against smallpox.

Why don't I have this scar? Didn't the vaccine work?

If you've recently been given a smallpox vaccine (for example, for a special duty) and haven't developed a rash, it's possible that the vaccine hasn't "taken." That means your body hasn't responded. But a doctor will notice this before you do.

A doctor will usually check the area for a blister within the first week after the vaccination. If no such signs appear, a repeat vaccination may be recommended.

For those who received the vaccine a long time ago, the scars may fade a little over time. This is normal.

Is there a connection between this scar and the newly-talked-about mpox vaccine?

Yes, there is a connection. Smallpox and mpox (formerly called monkeypox) are both caused by a very similar family of viruses. Therefore, the smallpox vaccine may provide some protection against mpox.

Currently, there are two main types of vaccines used to protect against measles. One is the ACAM2000™ vaccine that we talked about earlier. It definitely causes a scar.

The other vaccine is called JYNNEOS® . It has fewer side effects, so many countries use it for mpox. Whether or not the JYNNEOS® vaccine causes a rash depends on the method of administration. Let's look at the two methods in this way.

Let's also learn about keloid scars.

When a skin wound heals, some people develop a larger, swollen, and thicker scar than a normal scar. This is called a keloid scar . People who have had keloid scars before are more likely to develop a similar scar again if they are given the Intradermal injection. So if you have such a history, you should definitely tell your doctor. Then he or she will choose the most suitable injection method for you.

Does having a smallpox scar mean you are protected from measles?

This is the question that many people have. The answer is, "I can't say for sure, you need to ask your doctor to confirm."

Having a scar can provide some level of protection, but how strong that protection is depends on several factors:

• How long has it been since you were vaccinated? (Immunity starts to wane after 3-5 years).
• What vaccine did you get?
• How is your overall health?

So, don't just look at the scar and assume you're protected from Mpox. Your family doctor is the best person to know your vaccination history and the exact protection you need.