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Smallpox

What is smallpox?
Smallpox is a virus that used to cause one of the most feared illnesses in history. A global World Health Organization vaccination program from the mid-1960s to 1980 successfully eradicated smallpox. The last naturally occurring case of the disease appeared in 1977 in Somalia. Smallpox virus is maintained in high-security government laboratories in the United States and Russia. Though less contagious than influenza and chickenpox, single cases introduced into a population could result in large epidemics. Since most persons living today do not have any immunity to the virus, any re-introduction of smallpox could result in a global pandemic.

What are the symptoms of smallpox?
When smallpox naturally occurred, symptoms usually developed 12 to 14 days after exposure to another person with smallpox and included high fever, severe body aches, vomiting and a rash. The often painful rash usually appeared two to three days after the fever, first on the face, mouth, hands, forearms, palms or soles of the feet, spreading from those areas to the legs and the trunk. The rash would change to raised bumps and then pus-filled blisters over the course of a week. After about three weeks, the blisters would crust, scab, and fall off, often leaving a pitted scar.

What is bioterrorism?
Bioterrorism is the intentional use of biological agents, or germs, to cause illness, Bioterrorism has occurred in NYC only in 2001, when several media outlets received letters that were intentionally contaminated with anthrax bacteria.

What should I do if I think that I or someone I know has smallpox symptoms?
Anyone with fever and a new rash should be evaluated in a hospital immediately. Call 911.

Is smallpox fatal?

When smallpox occurred in the past, most patients recovered, though up to 30 percent of smallpox cases died from the disease.

How is smallpox spread?
Smallpox is spread person to person by:
  • Inhaling virus particles from an infected person’s cough.
  • Touching the rash or blisters of an infected person and then touching one’s own nose or mouth.
  • Handling clothing and bedding of an infected person.
Smallpox is contagious after an infected person has developed a fever and rash. Smallpox patients usually remain contagious until the scabs from the rash fall off. Individuals with smallpox, as well as those who may have been exposed to the virus, should be separated from those who have not yet been exposed.

How contagious is smallpox?
In the past, the chance of an unvaccinated person getting smallpox after being exposed to an infected person was 35 percent to 70 percent. In comparison, the chance of a susceptible person getting chickenpox or measles after being exposed to these diseases is 80 percent to 90 percent. Those at greatest risk of getting smallpox would be close, unvaccinated contacts of an infected individual, such as family members or healthcare workers.

How is smallpox diagnosed?
Doctors look for the symptoms of high fever, severe body aches, vomiting and a characteristic rash. Laboratory tests can also diagnose smallpox. Doctors conduct these tests in conjunction with the New York City Health Department and the Centers for Disease Control and Prevention (CDC).

Is there treatment for smallpox?
There is no known effective treatment for the disease once symptoms occur. However, vaccination within three days after exposure will probably offer some protection or could prevent the disease from becoming more severe. The smallpox vaccine also can stop the spread of the disease. New medications are being tested to treat smallpox after symptoms have appeared. Patients with smallpox need fever and pain medications, fluids and antibiotics if bacterial infections occur. Not all persons with smallpox disease would necessarily need to be treated in hospitals, which would be reserved for the most seriously ill patients.

What is smallpox vaccine?
The smallpox vaccine is a live virus vaccine that helps the body protects itself against the smallpox virus. It contains vaccinia virus, which is a different virus than the smallpox virus. The vaccine does not contain the smallpox virus, and cannot cause smallpox.
The vaccine is the best way to prevent smallpox. It is also the best way to prevent death in someone who has been exposed to the smallpox virus.

Is the vaccine available to the general public?
Yes. Because there is a smallpox outbreak and it is important to vaccinate people who have been or may become exposed to smallpox virus, the CDC is providing New York City with smallpox vaccine. The federal government has enough smallpox vaccine for the entire country.

If someone is exposed to smallpox, is it too late to get a vaccination?
No. An unvaccinated person exposed to the virus should be vaccinated within three days after exposure.

If I received smallpox vaccine in the past, am I still protected?
Protection against smallpox lasts for about three to five years. After five years, a smallpox vaccination may no longer provide full protection. However, someone who has been vaccinated sometime in their lives probably will have a less severe reaction to the smallpox virus than someone who has never been vaccinated. Most people in the United States received smallpox vaccine more than 30 years ago or have never been vaccinated. The United States stopped routinely vaccinating the general public in 1972.

How is the smallpox vaccine given?
The vaccine is given using a two-pronged needle that is dipped in a vaccine solution and used to prick a small area on the skin for a few seconds. The pricking is not deep, but it will cause soreness and a few drops of blood may appear. The vaccine is usually given on the outside of the upper arm.

How do you know if a smallpox vaccination is successful?
If the vaccination is successful, a red and itchy bump will form on the vaccine site in three to four days. About a week after vaccination, the bump will become a large blister, fill with pus, and then begin to drain. In about two weeks, the blister will begin to dry and a scab will form. The scab usually falls off about three weeks after the vaccination, leaving a small scar.

What are side effects of smallpox vaccination?
The blister and the scab that develop are normal reactions to the vaccine virus. Most people also have some itchiness, pain and swelling at the vaccination site. Other common side effects are fever, swollen lymph glands, fatigue, headache, nausea, muscle aches and redness at the vaccination site. In some people, the local swelling and redness can be severe but will usually improve on its own. Up to one-third of the people who receive the vaccine may become sick enough to miss some work. Most symptoms occur about one week after vaccination.

Can the vaccine have more serious side effects?
Some people may experience serious side effects from the smallpox vaccine but they are rare in people who do not have certain health problems or conditions. Severe reactions are also more common among people who receive the smallpox vaccine for the first time compared to persons who had been vaccinated at some other time in their lives. Most severe reactions to the vaccine can be treated. The treatment includes an injection of immune globulin and supportive therapy.
It is estimated that one or two people out of every 1 million people vaccinated may die from reactions to the vaccine. .

What pre-existing health problems and conditions might cause more severe smallpox vaccine side effects?
There are health problems that may put you or your close physical contacts at higher risk for a severe side effect from the smallpox vaccine. Anyone who has any of the following health conditions, or lives with or has close physical or sexual contact with someone with any of these conditions should follow Health Department recommendations about smallpox vaccine:
Weakened or compromised immune systems, due to HIV infection or AIDS, cancer, leukemia, lymphoma, organ transplants and autoimmune diseases, such as lupus. People who have problems producing antibodies or who are receiving chemotherapy, radiation therapy, high dose steroids (such as oral prednisone for more than two weeks) or other medicines that weaken the immune system. However, cancer survivors can be vaccinated if the cancer is cured, the person is no longer on chemotherapy or radiation therapy and the person’s doctor thinks that his or her immune system is normal and no longer weakened. If you have concerns about your health history, talk with your doctor.

A history of ever having had the skin diseases eczema or atopic dermatitis. People who have ever had red, patchy, scaly or itchy skin for more than two weeks that was not due to another cause, especially if the problem tended to come and go, may have had eczema or atopic dermatitis. Ask your doctor if you are not sure whether you have ever had these skin conditions.

Any active condition that causes breaks in the skin, such as burns, psoriasis, shingles, an allergic rash, impetigo or severe acne.

Women who are pregnant or who will be trying to get pregnant in the four weeks after vaccination.

Cardiac conditions with or without symptoms, including previous myocardial infarction, angina, congestive heart failure, cardiomyopathy, stroke or transient ischemic attack, chest pain or shortness of breath or other conditions under the care of a doctor.

Children younger than one year of age may be at higher risk for severe reactions (especially a brain infection called encephalitis) if they are exposed to vaccinia virus in the smallpox vaccine. Although the CDC does not currently list it as a reason not to be vaccinated, the New York City Health Department recommends that persons who live with a child younger than one year of age.
In addition to the conditions listed above, persons who have any of the following problems or conditions:

Women who are breastfeeding Anyone who is ill at the time they are to be vaccinated Anyone who is using steroid eye drops, and Anyone with allergies to one of the ingredients in the vaccine (polymyxin B, streptomycin, chlortetracycline, or neomycin) or with a severe allergy to latex (anaphylaxis reaction, including severe swelling, hives or difficulty breathing) Anyone with three or more of the following cardiac risk factors: hypertension, high cholesterol, diabetes, smoking, and having a first degree relative who had a heart condition before 50 years of age.

You may need to speak to your doctor to review your medical history to be sure you can be vaccinated. . Before you decide to get vaccinated, talk to your household and other close contacts to be sure they do not have any of the medical conditions listed above. They may need to speak with their doctors to be sure that they do not have any of those conditions.

Can the live vaccinia virus in the vaccination site be spread to other persons?
Yes. The virus in the smallpox vaccine is present at the site of the vaccination until it is completely healed and the scab falls off (about three weeks). Because the vaccine site contains a live virus, it can be spread to other people and other parts of the body. This can usually be prevented by not touching the vaccine site. Proper care of the vaccine site includes covering it with the recommended dressing, carefully washing your hands after touching the site or the dressing and disposing of used dressing materials in sealed or zip-locked plastic bags. Until it completely heals, you should keep the vaccination site bandaged and covered with long-sleeve clothing at all times, including while you sleep.

Are there any risks to my pets if I get the smallpox vaccine?
Smallpox is a disease of humans. However, the vaccinia virus in the vaccine can infect animals. Dogs have a very low risk of any reaction if they accidentally touch the vaccinia virus in the vaccination site, including the scab. Some animals, however, such as hamsters, may be more likely to have a reaction to an exposure. The best way to avoid a problem is to protect your pets from any possible contact with the vaccinia virus during the three week period after you have been vaccinated. To minimize the risk to pets and other animals while your vaccination site heals:

Do not let animals sniff or have any direct contact with the vaccination site or the bandages, clothing or sheets that touch the scab.
Keep pets out of the room when you are changing bandages or changing clothes.

Before allowing your pet back into the room after you have changed your bandage, carefully disinfect the bandage with bleach, dispose of it in a sealed plastic bag, put any clothing that had contact with your vaccination site in the laundry and wash your hands well.

Make sure that pets and rodents do not have access to trash containers that have contaminated bandages in them. Cover trash containers tightly and take them to an inaccessible area.

Wildlife biologists should consider avoiding handling and releasing live rodents for about three weeks after being vaccinated or until the scab falls off.

If your animal has any unusual symptoms, and it could have been accidentally exposed to vaccinia virus, contact the Health Department and your veterinarian.

What is bioterrorism?
Bioterrorism is the intentional use of biological agents, or germs, to cause illness. Bioterrorism has occurred in NYC only in 2001, when several media outlets received letters that were intentionally contaminated with anthrax bacteria.

How has New York City prepared for a potential smallpox outbreak?
The Health Department has developed a smallpox response plan with other city, state and federal agencies in the event that smallpox is detected anywhere in the world, including in New York City. The Department monitors disease trends, emergency department visits and 911 calls that might indicate that a bioterrorism attack has occurred. The Department also prepares to rapidly evaluate suspected bioterrorism-related illnesses and educates physicians.

How Will I Cope?
A smallpox outbreak in NYC can be very stressful, especially if it is large scale event. It can disrupt your everyday life and make you and those around you feel less safe. You may experience fear and uncertainty. Learning about stress and strategies to manage it can help you cope.

Prepare Today, Cope Better Tomorrow - Stress during Disasters provides basic information and practical advice on dealing with the stress and anxiety caused by disasters. It is available in seven languages.

If there is a smallpox outbreak in the city and you feel overwhelmed and unable to cope, or if you are concerned about someone else, you can find help by calling 1-800 LIFENET. LIFENET is a free, confidential helpline for New York City residents, available 24/7, with trained staff ready to take your calls and offer advice: 1-800-LifeNet 1-800-543-3638 (English), 1-877-Ayudese 1-877-298-3373 (Spanish), 1-877-990-8585 (Chinese), 1-212-982-5284 (TTY).

Where can I get more information?
For more information about smallpox fever, visit:

Centers for Disease Control and Prevention (CDC)