Smallpox vaccine and heart problems

The smallpox vaccine may cause myocarditis, pericarditis, or a combination of these conditions (myopericarditis). Between December 13, 2002, and March 31, 2003, 1 of every 20,000 people in the U.S. military who received the vaccine developed one of these problems. Most cases were mild or moderate, and those who were affected recovered.1

Chest pain (angina) and heart attack have occurred in a small number of people who have been vaccinated. Doctors are not certain whether the vaccine caused these problems or whether the people affected would have had heart problems even if they had not been vaccinated. Medical experts are studying this problem.

In the meantime, the U.S. Centers for Disease Control and Prevention (CDC) recommends against vaccinating people who have heart or circulation problems. This includes people who have:

Should I get the smallpox vaccine if there is an outbreak?

Research is still being done on this issue. Public health experts will say who should get the vaccine at that time.

What should I do if I am vaccinated and think that I am having a bad reaction?

Call a doctor right away. Tell him or her what is happening, the date and time that the reaction started, and when the vaccination was given. Your doctor will advise you what to do next.


  1. Centers for Disease Control and Prevention (2004). Smallpox vaccine and heart problems. Available online:

Last Updated: January 26, 2009

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