Questions & Answers
Smallpox - Vaccine - Cardiac Related Reactions
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Heart-Related Problems After Smallpox Vaccination

  1. What has the Department of Defense (DoD) seen in terms of heart inflammation after smallpox vaccination?

    The Department of Defense reported its first case of inflammation in or around the heart (myopericarditis) after smallpox vaccination in early February 2003. As of January 2008, DoD has identified 161 cases of acute myocarditis and/or pericarditis among 1.4M smallpox vaccinees, with symptoms appearing 7 to 19 days after vaccination. These people had clinical conditions that varied from mild to moderate; the condition was severe in two cases.

    Most cases occurred among those receiving smallpox vaccinations for the first time. Most cases occurred among men.

    The health of our people is foremost in our priorities. These cases were followed carefully to evaluate their recovery, at 27 hospitals in 21 states and several countries overseas. Detailed follow-up cardiac testing is available in 46 cases: all had normal electrocardiograms (EKGs), echocardiograms ("echos") and normal treadmill test results. Based on our data and European experience, we have reason to believe these people should recover and remain well.

  2. What is the difference between myopericarditis, myocarditis, and pericarditis?
    Myocarditis is an inflammation of heart muscle tissue (the myocardium). Pericarditis is an inflammation of the sac surrounding the heart (the pericardium). When both conditions occur at the same time or to group both categories together, it is called myopericarditis.

  3. Is there a relationship between the reported heart attacks and DoD's findings of myocarditis and/or pericarditis in smallpox vaccinees?
    Myocarditis and heart attacks are different diseases. Myocarditis involves inflammation of the heart muscle. Heart attacks are different, in that they involve problems with heart rhythm or blood vessels in the heart. At present, there is no evidence of a link between myocarditis and heart attacks. But DoD continues to investigate any possibilities of a relationship between vaccination and an adverse event.

  4. How does smallpox vaccine cause myocarditis or pericarditis?
    The precise cause is unknown; however, a reasonable theory is that the vaccinia virus in smallpox vaccine gets into the blood stream and then causes inflammation in the heart tissue.

  5. Was the finding of myopericarditis a surprise to DoD officials? Is this a new or previously unknown reaction?
    Because rare cases of myopericarditis have been reported previously following smallpox vaccination, notably in a study of Finnish military recruits in the 1980s, DoD was watching for the occurrence of myocarditis and was not surprised. In Finland, 1 in 10,000 vaccinees developed myopericarditis.

  6. How was the myocarditis or pericarditis diagnosed in service members?
    The patients with myocarditis and/or pericarditis sought medical care after developing chest pain. Blood tests showed that they had elevated levels of enzymes (such as CKMB or troponin), suggesting myocarditis or pericarditis. They had temporary changes in ECG (electrocardiogram) and/or echo-cardiogram readings.

Heart Conditions That Exempt Someone From Smallpox Vaccination

  1. Will DoD defer smallpox vaccination in people who have heart conditions?

    Yes. We will defer people with serious heart or blood vessel-related conditions. From the standpoint of military readiness, people with major heart conditions are unlikely to be in military service. Some examples include a history of angina, an earlier heart attack, artery disease, congestive heart failure, cardiomyopathy, stroke, "mini stroke", or chest pain or shortness of breath with activity (such as walking up stairs). If you have concerns about your health history, speak with your health care provider before vaccination.

    Similar to the CDC, and based on input from the American College of Cardiology, we will also defer people with three or more cardiac risk factors. The risk factors include:

    (1) current smoker or tobacco user,
    (2) high blood pressure,
    (3) high cholesterol or triglycerides,
    (4) high blood sugar,
    (5) a heart condition before age 50 in a parent, brother, or sister.

    Vaccination of other people should continue as planned.

    If you smoke, we encourage you to stop.

  2. What about people who had a smallpox vaccination when they were younger, and then later had a heart attack or heart condition? Should these people be deferred?
    Yes, if someone has a history of a serious heart condition, he or she should be deferred from receiving smallpox vaccine in a non-emergency situation. In the event of a smallpox outbreak, vaccination would be recommended.

  3. If somebody with a serious heart condition is exposed to the disease smallpox, should they get the smallpox vaccine?
    In most cases, experts agree, people directly exposed to the disease smallpox (i.e., variola virus) should get the smallpox vaccine. In an emergency situation, this would apply to people with serious heart conditions.

  4. I recently received the smallpox vaccination, and I have a history of heart conditions. What should I do?
    Unless you are experiencing symptoms, such as chest pain, difficulty breathing, shortness of breath, or pain radiating down your arm or to your neck, you shouldn't do anything special. If you start having these symptoms, you should seek medical care right away.