Heart symptoms subside in smallpox vaccines

Abnormalities are not long-term, data show

Military personnel who developed myopericarditis from the smallpox vaccine responded to treatment and did not have lasting, observable effects, according to a review of the cases published in the Journal of the American College of Cardiology.1

As of May 1, the military had vaccinated 615,000 individuals against smallpox; 71 of them reported symptoms of myocarditis or pericarditis — and/ or had changes in ECG or cardiac enzymes or evidence on an echocardiogram.

"So far, we continue to follow everybody out on our registry. We will follow them for at least two years, long term," says Dimitri C. Cassimatis, MD, cardiology fellow at Walter Reed Army Medical Center in Washington, DC. "Thus far, there have been no cases where objective abnormalities have continued long term. Everybody has recovered."

However, Cassimatis notes, "There are a few patients who continue to have some atypical chest pain symptoms that do not interfere with their life and have no objective abnormalities on testing. We don’t know what’s causing the persistent symptoms. In no way are they as severe as they were in the initial phase."

The military data clearly establish a link between the smallpox vaccine and myopericarditis. The rate of myopericarditis was about eight times higher among smallpox vaccinees than among a similar population who did not have the vaccine or had been previously vaccinated, Cassimatis says.

The major symptoms of fatigue and chest pain typically occur about eight to 14 days after vaccination, he says. The vaccinees have responded to nonsteroidal anti-inflammatory drugs, he says.

The military data did not show any link between the smallpox vaccine and other cardiac events.

Anyone who receives the smallpox vaccine is being screened for cardiac risk factors or a history of cardiovascular disease.


1. Cassimatis DC, Atwood JE, Engler RM, et al. Smallpox vaccination and myopericarditis: A clinical review. J Am Coll Cardiol 2004; 43:1503-1510.