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Emergency Preparedness
Smallpox
The Vaccine
What is the smallpox vaccine, and is it still required?
The smallpox vaccine is the only way to prevent smallpox. The vaccine is made from a virus called vaccinia, which is another pox-type virus related to smallpox. The vaccine helps the body develop immunity to smallpox. It was successfully used to eradicate smallpox from the human population.
Routine vaccination of the American public against smallpox stopped in 1972 after the disease was eradicated in the United States. Until recently, the U. S. government provided the smallpox vaccine only to a few hundred scientists and medical professionals who work with smallpox and similar viruses in a research setting. After the events of September and October, 2001, however, we have taken extensive actions to improve our level of preparedness against terrorism. For smallpox, this included updating a response plan and ordering enough smallpox vaccine to immunize the American public in the event of a smallpox outbreak. The plans are in place, and there is sufficient vaccine available to immunize everyone who might need it in the event of an emergency.
Should I get vaccinated against smallpox?
The smallpox vaccine is not available to the general public at this time. If vaccination is considered advisable, you will be notified quickly.
How is the vaccine given?
The smallpox vaccine is not given with a hypodermic needle. It is not a shot, like many vaccinations. The vaccine is given using a bifurcated (two-pronged) needle that is dipped into the vaccine solution. When removed, the needle retains a droplet of the vaccine. The needle is then used to prick the skin 15 times in a few seconds. The pricking is not deep, but it will cause a sore spot and one or two drops of blood to form. The vaccine usually is given in the upper arm.
If the vaccination is successful, a red and itchy bump develops at the vaccination site in three or four days. In the first week after vaccination, the bump becomes a large blister, fills with pus, and begins to drain. During week two, the blister begins to dry up and a scab forms. The scab falls off in the third week, leaving a small scar. People who are being vaccinated for the first time have a stronger reaction than those who are being revaccinated.
If someone is exposed to smallpox, is it too late to get a vaccination?
Vaccination within 3 days of exposure will completely prevent or significantly modify smallpox in the vast majority of persons. Vaccination 4 to 7 days after exposure likely offers some protection from disease or may modify the severity of disease.
How long does a smallpox vaccination last?
Past experience indicates that the first dose of the vaccine offers protection from smallpox for 3 to 5 years, with decreasing immunity thereafter. If a person is vaccinated again later, immunity lasts longer.
Are diluted doses of smallpox vaccine as effective?
Recent tests have indicated that diluted smallpox vaccine is just as effective in providing immunity as full-strength vaccine.
Vaccinia
What is the smallpox vaccine made of?
The vaccine is made from a virus called vaccinia, another pox-type virus related to smallpox. The smallpox vaccine helps the body develop immunity to smallpox.
Is it possible for people to get smallpox from the vaccination?
No. The smallpox vaccine does not contain smallpox virus and cannot spread or cause smallpox. However, the vaccine does contain another virus called vaccinia which is live in the vaccine. Because the virus is alive, it can spread to other parts of the body or to other people from the vaccine site. For that reason, the vaccine site must be carefully monitored.
Is it possible to get vaccinia, the virus in the vaccine, from someone who has recently been vaccinated?
Yes. Vaccinia is spread by touching a vaccination site before it has healed or by touching bandages or clothing that have become contaminated with live virus from the vaccination site. Vaccinia is not spread through airborne contagion. The vaccinia virus may cause rash, fever, and head and body aches.
What are the symptoms of vaccinia?
The vaccinia virus may cause rash, fever, and head and body aches.
How is vaccinia spread?
Vaccinia is spread by touching a vaccination site before it has healed or by touching bandages or clothing that have become contaminated with live virus from the vaccination site. Vaccinia is not spread through the air.
Vaccine Safety
How safe is the smallpox vaccine?
The smallpox vaccine is the best protection you can get if you are exposed to the smallpox virus. Most people experience normal, usually mild reactions that include a sore arm, fever, and body aches. In recent tests, one in three people felt bad enough to miss work, school, or recreational activity or had trouble sleeping after receiving the vaccine.
However, the vaccine does have some more serious risks. In the past, about 1,000 people for every 1 million people vaccinated experienced reactions that, while not life-threatening, were serious. These reactions include a vigorous (toxic or allergic) reaction at the site of the vaccination and spread of the vaccinia virus (the live virus in the smallpox vaccine) to other parts of the body and to other people. These reactions typically do not require medical attention. Rarely, people have had very bad reactions to the vaccine.
In the past, between 14 and 52 people per 1 million vaccinated experienced potentially life-threatening reactions, including eczema vaccinatum, progressive vaccinia (or vaccinia necrosum), or postvaccinal encephalitis. Based on past experience, it is estimated that between 1 and 2 people out of every 1 million people vaccinated will die as a result of life-threatening reactions to the vaccine.
Careful screening of potential vaccine recipients is essential to ensure that those at increased risk do not receive the vaccine. People most likely to have side effects are people who have, or even once had, skin conditions, (especially eczema or dermatitis) and people with weakened immune systems, such as those who have received a transplant, are HIV positive, or are receiving treatment for cancer.
Anyone who falls within these categories, or lives with someone who falls into one of these categories, should NOT get the smallpox vaccine unless they are exposed to the disease.
Pregnant women should not get the vaccine because of the risk it poses to the fetus. Anyone who is allergic to the vaccine or any of its components should not get the vaccine, and anyone under the age of 18 should not get the vaccine unless they are exposed to smallpox.
Who should NOT get the vaccine?
People who should not get the vaccine include anyone who is allergic to the vaccine or any of its components (polymyxin B, streptomycin, chlortetracycline, neomycin); pregnant women; women who are breastfeeding; people who have, or have had, skin conditions (especially eczema and dermatitis); and people with weakened immune systems, such as those who have received a transplant, are HIV positive, are receiving treatment for cancer, are taking medications (like steroids) that suppress the immune system, or have heart conditions.
Also individuals younger than 12 months of age should not get the vaccine. Additionally, the Advisory Committee on Immunization Practices (ACIP) advises against non-emergency use of smallpox vaccine in children younger than 18 years of age and the vaccine manufacturer's package insert states that the vaccine is not recommended for use in geriatric populations in non-emergency situations.
The term geriatric generally applies to those people age 65 and above. These people should not receive the vaccine unless they have been exposed to smallpox. Also, people who are using steroid drops in their eyes should wait until they are no longer using the medication to get the vaccine.
Should I get the vaccine if I have heart problems?
Careful monitoring of smallpox vaccinations given over recent months has suggested that the vaccine may have caused side effects on the heart. There have been reports of heart pain (angina), heart inflammation (myocarditis), inflammation of the membrane covering the heart lining (pericarditis), and/or a combination of these two problems (myopericarditis). Experts are exploring this more in depth.
As a precaution, if you have been diagnosed by a doctor as having a heart condition with or without symptoms you should NOT get the smallpox vaccine at this time. These include conditions such as known coronary disease and/or three or more of the following risk factors:
- You have been told by a doctor that you have high blood pressure.
- You have been told by a doctor that you have high blood cholesterol.
- You have been told by a doctor that you have diabetes or high blood sugar.
- You have a close relative (mother, father, brother, or sister) who had a heart condition before the age of 50.
- You smoke cigarettes now.
Is there any way to treat bad reactions to the vaccine?
Vaccinia Immune Globulin (VIG) can help people who have certain serious reactions to smallpox vaccine. A second drug, cidofovir, may be used is some situations. Neither drug is currently licensed for this purpose (both administered under investigational new drug (IND) protocol) nor may they have side effects of their own.
Is a child under the age of 1 year in the household a contraindication to vaccination?
Vaccinated parents of young children need to be careful not to inadvertently spread the virus to their children. They should follow site care instructions that are essential to minimizing the risk of contact transmission of vaccinia.
These precautions include:
- Covering the vaccination site,
- Wearing a sleeved shirt, and
- Careful hand washing anytime after touching the vaccination site or anything that might be contaminated with virus from the vaccination site.
If these precautions are followed, the risk for children is very low. Individuals who do not believe that they can adhere to such instructions should err on the side of caution and not be vaccinated at this time.
Are there any eye conditions that would preclude vaccination?
The concern surrounding eyes is that frequent touching of the eyes by someone who has gotten the smallpox vaccine may increase the chances that that person will experience spread of the vaccinia virus to the eyes (inadvertent inoculation of the eye) by touching the vaccine site or something contaminated with live virus and then touching their eyes before they wash their hands. This side effect is a serious one because it can lead to damaged vision, or even blindness.
People who wear contact lenses, or touch their eyes frequently throughout the day can get the smallpox vaccine, but they must be especially careful to follow instructions for care of the smallpox vaccination site. Frequent and thorough hand washing will minimize the chance of contact spread of the vaccinia virus.
As an additional precaution to minimize the risk of this type of transmission in selected groups of people, the Advisory Committee on Immunization Practices (ACIP) decided that anyone with eye diseases or other conditions (e.g., recent LASIK surgery) that require the use of corticosteroid drops in the eye should wait until they no longer require such treatment before getting vaccinated.