Incidence and follow-up of inflammatory cardiac complications after smallpox vaccination.

OBJECTIVES: The purpose of this study was to assess the follow-up of patients with vaccinia-associated myocarditis. BACKGROUND: With the threat of biological warfare, the U.S. Department of Defense resumed a program for widespread smallpox vaccinations on December 13, 2002. One-year afterwards, there has been a significant increase in the occurrence of myocarditis and pericarditis among those vaccinated. METHODS: Cases were identified through sentinel reporting to military headquarters, systematic surveillance, and spontaneous reports. RESULTS: A total of 540,824 military personnel were vaccinated with a New York City Board of Health strain of vaccinia from December 2002 through December 2003. Of these, 67 developed myopericarditis at 10.4 +/- 3.6 days after vaccination. The ST-segment elevation was noted in 57%, mean troponin on admission was 11.3+/- 22.7 ng/dl, and peak cardiac enzymes were noted within 8 h of presentation. On follow-up of 64 patients (96%) at a mean of 32 +/- 16 weeks, all patients had objective normalization of echocardiography, electrocardiography, laboratory testing, graded exercise testing, and functional status; 8 (13%) reported atypical, non-limiting persistent chest discomfort. CONCLUSIONS: Post-vaccinial myopericarditis should be considered in patients with chest pain within 30 days after smallpox vaccination. Normalization of echocardiography, electrocardiography, and treadmill testing is expected, and nearly all patients have resolution of chest pain on follow-up.

Myopericarditis following smallpox vaccination among vaccinia-naive US military personnel.

CONTEXT: In the United States, the annual incidence of myocarditis is estimated at 1 to 10 per 100,000 population. As many as 1% to 5% of patients with acute viral infections involve the myocardium. Although many viruses have been reported to cause myopericarditis, it has been a rare or unrecognized event after vaccination with the currently used strain of vaccinia virus (New York City Board of Health). OBJECTIVE: To describe a series of probable cases of myopericarditis following smallpox vaccination among US military service members reported since the reintroduction of vaccinia vaccine. DESIGN, SETTING, PARTICIPANTS: Surveillance case definitions are presented. The cases were identified either through sentinel reporting to US military headquarters surveillance using the Defense Medical Surveillance System or reports to the Vaccine Adverse Event Reporting System using International Classification of Diseases, Ninth Revision. The cases occurred among individuals vaccinated from mid-December 2002 to March 14, 2003. MAIN OUTCOME MEASURE: Elevated serum levels of creatine kinase (MB isoenzyme), troponin I, and troponin T, usually in the presence of ST-segment elevation on electrocardiogram and wall motion abnormalities on echocardiogram. RESULTS: Among 230,734 primary vaccinees, 18 cases of probable myopericarditis after smallpox vaccination were reported (an incidence of 7.8 per 100,000 over 30 days). No cases of myopericarditis following smallpox vaccination were reported among 95,622 vaccinees who were previously vaccinated. All cases were white men aged 21 years to 33 years (mean age, 26.5 years), who presented with acute myopericarditis 7 to 19 days following vaccination. A causal relationship is supported by the close temporal clustering (7-19 days; mean, 10.5 days following vaccination), wide geographic and temporal distribution, occurrence in only primary vaccinees, and lack of evidence for alternative etiologies or other diseases associated with myopericarditis. Additional supporting evidence is the observation that the observed rate of myopericarditis among primary vaccinees is 3.6-fold (95% confidence interval, 3.33-4.11) higher than the expected rate among personnel who were not vaccinated. The background incidence of myopericarditis did not show statistical significance when stratified by age (20-34 years: 2.18 expected cases per 100,000; 95% confidence interval [CI], 1.90-2.34), race (whites: 1.82 per 100,000; 95% CI, 1.50-2.01), and sex (males: 2.28 per 100,000; 95% CI, 2.04-2.54). CONCLUSION: Among US military personnel vaccinated against smallpox, myopericarditis occurred at a rate of 1 per 12 819 primary vaccinees. Myopericarditis should be considered an expected adverse event associated with smallpox vaccination. Clinicians should consider myopericarditis in the differential diagnosis of patients presenting with chest pain 4 to 30 days following smallpox vaccination and be aware of the implications as well as the need to report this potential adverse advent.

Myopericarditis following smallpox vaccination.

Myopericarditis has been a rare or unrecognized event after smallpox vaccinations with the New York City Board of Health strain of vaccinia virus (Dryvax; Wyeth Laboratories, Marietta, Pennsylvania). In this article, the authors report an attributable incidence of at least 140 clinical cases of myopericarditis per million primary smallpox vaccinations with this strain of vaccinia virus. Fifty-eight males and one female aged 21-43 years with confirmed or probable acute myopericarditis were detected following vaccination of 492,730 US Armed Forces personnel from December 15, 2002, through September 30, 2003. The cases were identified through sentinel reporting to military headquarters, active surveillance using the Defense Medical Surveillance System, or reports to the Vaccine Adverse Event Reporting System. The observed incidence (16.11/100,000) of myopericarditis over a 30-day observation window among 347,516 primary vaccinees was nearly 7.5-fold higher than the expected rate of 2.16/100,000 (95% confidence interval: 1.90, 2.34) among nonvaccinated, active-duty military personnel, while the incidence of 2.07/100,000 among 145,155 revaccinees was not statistically different from the expected background rate. The cases were predominantly male (58/59; 98.3%) and White (51/59; 86.4%), both statistically significant associations (p = 0.0147 and p = 0.05, respectively).