Smallpox Vaccine and Eczema: Is It Safe?

Vaccines have saved untold numbers of lives over the years, and the disease of smallpox has been virtually eradicated by vaccination. People who could be exposed to smallpox in laboratory settings and select military divisions still get the smallpox vaccine. In 2022, public health authorities also authorized the smallpox vaccine to prevent mpox (formerly known as monkeypox).

However, the traditional form of smallpox vaccine poses serious risks to people with eczema (atopic dermatitis). They can develop a severe and even life-threatening infection called eczema vaccinatum. Instead, they must get a different form of smallpox vaccine.

Here's what's important to know about eczema and the smallpox vaccine, including which type of vaccine to get, side effects, risks, and where and when to get the vaccine.

Is the Smallpox Vaccine Safe and Effective for People With Eczema?

The smallpox vaccine is so effective that most countries stopped giving it to the general public in the early 1970s as the spread of smallpox was eradicated. According to the Centers for Disease Control and Prevention (CDC), the vaccine prevented smallpox in 95% of the people who received it.

In August 2022, a new form of smallpox vaccine (JYNNEOS) was granted an Emergency Use Authorization (EUA) to protect people in the United States against mpox.

Though every vaccine must pass rigorous development and testing procedures for safety in the United States, the standard smallpox vaccine does pose a risk in certain people. The new vaccine gives them a safe option.

The traditional smallpox vaccine contains a live virus called vaccinia, which is not the smallpox virus (variola) and can't give you smallpox. However, if you have ever had eczema, the vaccinia virus can lead to an infection called eczema vaccinatum.

Eczema vaccinatum leads to widespread rashes and a serious illness that can be life-threatening. While most people can take the traditional smallpox vaccine, it is not safe for people with a history of eczema.

Which Type Should People With Eczema Get?

People with eczema should not get a traditional smallpox vaccine. Instead, they should get the JYNNEOS vaccine (brand names include Imvamune and Imvanex). It contains vaccinia that has been weakened and cannot replicate, meaning it can't spread to the rest of the body and cause infection.

JYNNEOS is approved for the prevention of both smallpox and mpox. If you are at risk for mpox and want a vaccine, make sure you let your healthcare provider know if you have ever had eczema, even once, and understand which vaccine you're getting.

For people who have never had eczema, the traditional smallpox vaccine, called ACAM2000, is safe as a preventive for both smallpox and mpox. It contains a live virus that replicates at the site of inoculation (where in your body you get the shot).

People who get the ACAM2000 vaccine should keep the site covered. They should take care to avoid skin-to-skin contact or sharing towels or blankets for about four weeks (till the vaccination site has healed) with someone who has or has had eczema or a weakened immune system, babies under 1 year old, or people who are pregnant.

Are There Side Effects of the Smallpox Vaccine?

There are some typical mild side effects with either form of the smallpox vaccine. They are more frequent in those who have the ACAM2000 than the JYNNEOS vaccine. Side effects include:

• Tiredness
• Headache
• Muscle pain
• Redness, soreness, itching, or swelling at the injection site

There have been no severe side effects in people with eczema who have had the JYNNEOS vaccine. The injection is given in the deepest layer of skin. It is given in two doses that are 28 days apart.

An alternative method is to inject it into the outer layers, which may make the side effects a little more severe and the redness may last for six months or more. If you tend to develop raised (keloid) scars, let your healthcare provider know. People who have allergies to any of the ingredients in the JYNNEOS vaccine should not have it.

If you do not have eczema and get the ACAM2000 vaccine, the provider will prick the skin on your upper arm a few times with a two-pronged needle dipped in a vaccine solution. The virus causes an infection at the site, and you'll develop a red, itchy sore, which means the vaccine is working. The sore will heal in a few weeks and leave a small scar.

The ACAM2000 vaccine is not recommended for people with eczema or people who:

• Have a weakened immune system from disease, cancer therapy, or autoimmune disease
• Are taking medications that weaken the immune system
• Have an active skin injury or disease like burns, wounds, impetigo, shingles, psoriasis, or chicken pox
• Are pregnant or planning to become pregnant within one month of vaccination

The ACAM2000 vaccine can, rarely, cause serious heart problems including myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the heart lining) for up to a month after vaccination. With treatment, most people improve within weeks, but, although rare, it can be fatal.

Call your healthcare provider or get emergency help right away if you have:

• Chest pain or pressure
• Fast or irregular heartbeat
• Breathing problems

People should not get a smallpox vaccine unless they know they've been exposed to smallpox or mpox, if they:

• Have heart disease
• Are breastfeeding
• Use ocular steroid medications
• Had a past allergic reaction to the vaccine or ingredients including gentamicin, ciprofloxacin, or chicken or egg protein.
• Are under age 18
• Have had mpox

If you have ever had eczema, the ACAM2000 vaccine is unsafe for you. If you contract eczema vaccinatum, symptoms include smallpox-like blisters. The illness can develop into a sepsis-like infection that can be fatal.

If you think you have eczema vaccinatum, seek medical care immediately. A medication called vaccinia immune globulin (VIG) treats eczema vaccinatum, but it should be given as soon as possible.

Risks of Smallpox or Mpox in People With Eczema

More than 30 million people in the United States have eczema. They could be at risk for mpox or, extremely rarely, smallpox. Having eczema does not make you more likely than other people to get either disease, but it does put you at high risk for eczema vaccinatum if you are vaccinated with the traditional vaccine.

An outbreak of mpox emerged in the United States in May 2022. Symptoms include a rash and flu-like symptoms that typically last from two to four weeks. The antiviral drug TPOXX is a treatment for people with mpox.

What Should People Avoid Before Having the Smallpox Vaccine?

The vaccine may interact with a number of prescription medications, including steroids and other immunosuppressants. Tell your healthcare provider about every medication you take before getting the vaccine.

If you've ever had eczema, do not touch the skin of a person who has received the traditional vaccine until their injection site has completely healed, when the scab falls off.

If you do come into contact with someone who has been vaccinated with the traditional vaccine, or even touch something they may have touched, wash the area with soap and warm water immediately. If you feel any symptoms or notice a rash, contact your healthcare provider immediately.

Where Does the Smallpox Vaccine Come From?

The original smallpox vaccine was developed in 1796 when English surgeon Edward Jenner inoculated a 13-year-old-boy with a vaccine made from material from sores caused by the cowpox virus and showed it gave immunity.

In the 19th century, the vaccinia virus replaced the cowpox virus for use in vaccination (how this occurred is still unknown). A program of mass immunization eradicated the disease around the world by 1979.

The JYNNEOS vaccine, approved in 2019, is made from a weakened form of the vaccinia virus that cannot replicate in your system and cannot cause smallpox or mpox. The modified vaccinia virus is grown in chicken embryo cells and then purified and filtered.

Where Can You Get the Smallpox Vaccine?

Until 2022, the smallpox vaccine was stockpiled because it was no longer needed in the general population. The availability of the two types of vaccines varies across the United States.

Eligibility for mpox vaccines depends on where you live. Contact your local health department to see if you qualify for the vaccine, or go online to the federal government's site to find a location near you.

When Should You Have the Smallpox Vaccine?

If you are at risk for mpox, consider having a smallpox vaccine. If you have the JYNNEOS vaccine, the protection will start to build with the first shot and you'll have full immunity two weeks after the second shot.

Research indicates that the vaccine can reduce the risk of infection even after you've been exposed if you are vaccinated within four days of exposure. It can help you avoid serious illness if you get it within two weeks of exposure. The ACAM2000 vaccine, which is given in one dose, takes full effect in about a month.

Summary

If you have ever had eczema, you should not have the traditional smallpox vaccine, either to protect against the very low risk of smallpox or an outbreak of mpox. Instead, you should get a form of the vaccine called JYNNEOS, which is safe and effective for people with eczema.

Other smallpox vaccines pose a serious and even life-threatening risk to people with eczema due to an infection called eczema vaccinatum. If you are considering getting a smallpox vaccine, it is essential that you tell the vaccine provider if you have ever had eczema.

A Word From Verywell

When mpox arrived on the scene in 2022, there was a lot of media buzz around it. Because transmission of the virus is higher in certain areas and among certain groups of people, it was important to let people know who was most at risk and to encourage they get immunized accordingly.

Mpox is rarely fatal, but it brings with it a rash and flu-like symptoms. You can spread it to other people. Make sure any information you get about the disease or the vaccination is from a trusted source.