Smallpox Vaccine
all information

Smallpox Vaccine

En Español (Spanish Version)

What Is Smallpox?

Smallpox is an infectious disease that is caused by a virus, and at one time was one of the world’s most feared infections. Smallpox has no treatment or cure, and can be fatal. Because of a worldwide vaccination effort, smallpox is virtually nonexistent. The last case of smallpox in the US was in 1949. Because there have been no cases of smallpox reported anywhere, the vaccine is no longer administered.

However, because of threats of bioterrorism, it’s important to remember the facts about smallpox in case another outbreak should occur.

Smallpox can be transmitted from person to person via direct, face-to-face contact, typically prolonged. It can also be transmitted through bodily fluids or linens and clothing that have been contaminated with the virus. Smallpox can be contracted through the air, although transmission in that manner is rare. The virus can only be transmitted through humans, not insects or animals.

The primary symptoms of smallpox include:

  • High fever
  • Headache
  • Body aches
  • Vomiting

As the virus progresses, a red rash begins to appear on the tongue and in the mouth. The rash then spreads, and the spots begin to break open.

The rash spreads across the entire body, and eventually turns from red spots into raised bumps. By about the fourth day, the bumps fill with fluid and have a depression in the middle of the bump. Eventually, scabs form over all of the bumps.

What Is the Smallpox Vaccine?

The smallpox vaccine contains a live virus, called the vaccinia virus, which is related to smallpox. The vaccine is administered subcutaneously (under the skin) with a bifurcated (two-pronged) needle that has been dipped into the vaccine.

Who Should Get Vaccinated and When?

People who have come into contact with, or have the potential to come into contact with, the smallpox virus should be vaccinated. The vaccine is not currently administered to the general public. Certain military personnel who work in potentially high-threat areas do receive the smallpox vaccination.

The vaccine is considered typically effective for 3-5 years.

What Are the Risks Associated With the Smallpox Vaccine?

Because a live virus is injected into the skin during the vaccination, it is possible for the virus to spread to other areas of the body, or even other people. The injection site must be well-protected to prevent spreading the virus after vaccination.

Common side effects of smallpox vaccine include:

  • Rash
  • Fever
  • Headache
  • Body aches
  • Soreness in the arm

Who Should Not Get Vaccinated?

The following individuals should not get vaccinated:

  • Pregnant or breastfeeding women
  • Children less than 12 months old
  • People who have had a previous allergic reaction to the vaccine or any of its components
  • People with eczema or who have had a history of eczema, or other skin conditions such as atopic dermatitis
  • People with skin conditions such as burns , chickenpox , shingles , impetigo , herpes , severe acne , or psoriasis . People with these conditions should not get vaccinated until the conditions have healed.
  • People with heart disease, heart conditions, multiple risk factors for heart disease, or stroke-like symptoms
  • People with weakened immune systems (eg, those who have received a transplant, have HIV, are receiving cancer treatment, or are currently taking medications that suppress the immune system, including steroids)

There are other conditions that you may have in which vaccination should be avoided. Talk to your doctor about your conditions before getting vaccinated.

What Happens in the Event of an Outbreak?

If an outbreak should occur, the United States has a large supply of the smallpox vaccine to vaccinate the entire US population.


Centers for Disease Control and Prevention

Department of Health & Human Services


US Department of Health & Human Services website. Available at: . Accessed June 13, 2007.

The White House website. Available at: . Accessed February 6, 2007.

World Health Organization website. Available at: . Accessed February 6, 2007.

Last reviewed February 2008 by David Horn, MD, FACP

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

Your Health and Happiness