The smallpox vaccine is a way to protect you against infection by the smallpox virus. Smallpox is a very serious illness that can spread from person to person by coughing or sneezing. It causes high fever, tiredness, headache, backache, and a rash. The rash can cause severe, permanent scarring. Smallpox causes death for about 1 of every 3 people who get the disease. There is no cure for smallpox.
If you get the vaccine before you are exposed to smallpox, you will be protected from the disease. If you are exposed to the smallpox virus and get vaccinated within 3 days of the exposure, the vaccination usually prevents or reduces the symptoms of smallpox. Vaccination 4 to 7 days after exposure offers some protection from the disease or makes it less severe.
Routine smallpox vaccination among the American public stopped in 1972 when no more cases of smallpox were being reported in the US. The smallpox vaccine is not given unless you are at high risk, such as being in the military or doing research on smallpox.
In 2001 the US government ordered enough smallpox vaccine to immunize the American public if there is a smallpox outbreak caused by terrorists.
Who should not get the smallpox vaccine?
You should not get the vaccine if:
You are pregnant or breast-feeding. It might harm the baby.
You are younger than 18 years of age (unless it is an emergency, such as a smallpox epidemic or outbreak).
You have a weakened immune system from conditions such as HIV/AIDS, an organ transplant, or from cancer chemotherapy, radiation therapy, or steroid medicine. If you are taking chemotherapy for a condition other than cancer, such as rheumatoid arthritis, ask your healthcare provider if you should have the vaccine.
You have heart disease.
How is the vaccine given?
You will not get a shot. Instead, your healthcare provider will dip a two-pronged needle into the vaccine and prick your skin 5 to 15 times. The poking is not deep, but it will cause a little bleeding and a small sore on your skin. The vaccine usually is given in the upper arm.
A red, itchy bump will develop at the vaccine site in 3 or 4 days. In a week, the bump becomes a blister, fills with pus, and begins to drain. During the second week, the blister begins to dry up and a scab forms. The scab falls off in the third week, leaving a small scar.
The live virus is present at the vaccine site for up to 3 weeks after you get the vaccine. During this time the virus can spread to other parts of your body or to other people by direct contact. To help protect yourself from side effects and to keep from spreading the virus to others:
Follow your healthcare provider’s instructions for caring for the spot where you got the vaccine.
Keep the vaccine site covered with a loose bandage until the dry scab forms.
Try to avoid touching the place where you were vaccinated, even though it will itch as it starts to heal.
For the 3 weeks right after your vaccination, always wash your hands with alcohol-based cleansers or with soap and water after you touch the site and before you touch others.
If someone in your household got the vaccine, it is possible that they can spread the live virus to you. The infection that you can get from the vaccine is called vaccinia and it is not the same as smallpox. The infection is usually not serious in healthy people, but can cause sores on your skin. If it gets in your eyes, it can cause permanent damage. To prevent spreading the virus, take these precautions for 2 to 3 weeks, until the scab drops off:
Don’t touch the vaccine site until it’s healed. Don’t touch bandages, clothing, towels, or any material that might have come into contact with the live virus. Keep a separate laundry hamper for clothing, towels, or bedding that have come in contact with the vaccine site or drainage from the site. Wash these items in warm water with detergent or bleach. Wash your hands carefully after touching these items.
Make sure the person wears a gauze bandage held in place with tape over the vaccination site. They should not use a bandage that blocks air from the vaccination site. For extra protection they can wear a shirt that covers the site.
The vaccine site often gets itchy, so they may scratch, rub, or touch the site. If their hand is contaminated and they touch you, they can spread the virus to you. They should always wash their hands with soap and water or with alcohol-based cleansers after touching the site or the bandages and before touching others.
What are possible side effects?
Mild reactions you may have are:
Redness in the area where the vaccine was given
Large, sore glands in the armpits
These mild reactions usually go away without treatment.
Reactions that might need medical care include:
A rash or outbreak of sores limited to one area. This is caused by touching the vaccine site and then touching another part of the body, such as the genitals or face. If you touch your eyes, the virus can damage your sight or lead to blindness.
A widespread rash. This can happen when the virus spreads from the vaccine site into the blood. Sores can then break out on more than one part of the body.
A toxic or allergic rash called erythema multiforme. This rash can be all over the body, with flat, red patches, or bumps. They may look like targets with a red center, a lighter area around the red center, and then a red outer ring.
If you start having chest pain, shortness of breath, or other symptoms of heart disease, you should get medical care right away.
Developed by RelayHealth.
Adult Advisor 2015.1 published by RelayHealth. Last modified: 2014-05-07 Last reviewed: 2014-05-07
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Smallpox Vaccine: References
Centers for Disease Control and Prevention. Medication Guide Smallpox (Vaccinia) Vaccine, Live ACAM2000. US Dept of health and Human Services, Centers for Disease Control and Prevention. 10/2009. Accessed 4/2014 from
Centers for Disease Control and Prevention. Emergency Preparedness and Response. Smallpox Vaccine Overview. Feb. 7, 2007. US Dept. of Health and Human Services. Centers for Disease Control and Prevention. Accessed April 29, 2010 from http://www.bt.cdc.gov/agent/smallpox/vaccination/facts.asp.