Routine vaccination of Americans against smallpox stopped in 1972 after the disease was eradicated in the United States. However, in response to threats of biological warfare, the US government ordered enough smallpox vaccine to immunize the American public in the event of a smallpox outbreak. The smallpox vaccine is the most effective way to prevent smallpox, but the vaccine is not without its risks.
Smallpox is a serious, contagious, and sometimes fatal infectious disease that begins with a high fever, malaise, head and body aches, and sometimes vomiting. These symptoms are quickly followed by a specific rash, which spreads and progresses to raised bumps and pus-filled blisters that crust, scab, and fall off after about three weeks, leaving a pitted scar.
Smallpox is caused by the variola virus and is generally transmitted by direct contact with an infected person. It can also be spread through direct contact with infected bodily fluids or contaminated objects such as bedding or clothing.
A person with smallpox is sometimes contagious with the onset of fever, but the person becomes most contagious and very sick with the onset of rash. The infected person is contagious until the last smallpox scab falls off.
At the present time, there is no proven treatment for smallpox.
Smallpox was eradicated from the human population in 1980 following worldwide vaccination. If another outbreak of smallpox occurred, vaccination would be used to prevent it from spreading to other people. If vaccination takes place within three days of exposure to the smallpox virus, it can prevent or significantly decrease the severity of smallpox symptoms in most people.
The smallpox vaccine is made from a virus called vaccinia , a “pox”-type virus related to smallpox, which helps the body develop immunity to smallpox. It provides high-level immunity for 3-5 years and is effective in preventing smallpox in 95% of people vaccinated.
The smallpox vaccine is given using a two-pronged needle. The needle is used to prick the skin a number of times in a few seconds. The pricking is not deep, but it causes slight bleeding and a sore spot. The vaccine is usually given in the upper arm.
Normal Reactions
If the vaccination was successful, the following signs occur:
These are normal reactions that usually go away without treatment. They tend to be stronger in those vaccinated for the first time.
Serious Reactions
In the past, about 1,000 people out of every one million people vaccinated for the first time experienced serious, but not life-threatening reactions. These reactions may require medical attention and include:
Life-threatening Reactions
In the past, 14-52 people per one million people vaccinated for the first time experienced potentially life-threatening reactions. These reactions require immediate medical attention and include:
People with certain medical conditions, such as those with weakened immune systems or certain skin and heart conditions, are more likely to have reactions that are serious. The US Centers for Disease Control and Prevention (CDC) says they should not get the smallpox vaccine unless they have been exposed to smallpox.
After vaccination, it’s very important to follow skin care instructions for the vaccine site. Because the smallpox vaccine contains “live” vaccinia virus (not dead virus, like many other vaccines), it can spread to other parts of the body, or to other people. The vaccinia virus in the vaccine may cause rash, fever, and head and body aches. It can spread to other people by touching the vaccination site before it has healed or by touching bandages and clothing that have become contaminated with live virus from the vaccine site.
CDC Recommendations
The Centers for Disease Control and Prevention recommend the following precautions after receiving the smallpox vaccination:
According to the CDC, people who have any of the following conditions, or live with someone who does, should NOT get the smallpox vaccine unless they have been exposed to the smallpox virus :
In addition, individuals should not get the smallpox vaccine if they:
The CDC recommends that in the event of a bioterrorist event or other exposure to the smallpox virus, every exposed person should get the vaccine, regardless of their health status. Consult your physician if you have any questions about this recommendation.
In the wake of terrorist threats of biological warfare, many healthcare and public health workers are being vaccinated so that they can protect others, in the event of a smallpox outbreak. At the moment, however, the smallpox vaccine is not available to the general public. If an outbreak occurs, there is enough smallpox vaccine to vaccinate everyone in the US. Production of new vaccine is underway, but hopefully there will never again be a need to use it.
RESOURCES:
Centers for Disease Control and Prevention
http://www.cdc.gov/
National Institutes of Health
http://www.nlm.nih.gov/
US Department of Health and Human Services
http://www.smallpox.gov/
References:
Smallpox. Centers for Disease Control and Prevention website. Available at: http://emergency.cdc.gov/agent/smallpox/ . Accessed April 15, 2009.
Smallpox. US Department of Health and Human Services website. Available at: http://www.smallpox.gov/. Accessed March 13, 2003.
Last reviewed January 2009 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.
Copyright © 2007 EBSCO Publishing All rights reserved.