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 atopic 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 atopic 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) and they may 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.