Primary smallpox vaccination with the Dryvax strain was associated with a nearly 7.5-fold higher incidence of myopericarditis (16.11/100,000) compared to the expected background rate (2.16/100,000).
Observational (n=492,730)
Yes
Does smallpox vaccination increase the incidence of acute myopericarditis in US Armed Forces personnel?
Primary smallpox vaccination with the Dryvax strain is associated with a significantly increased risk of acute myopericarditis compared to background rates in military personnel.
Effect estimate: 7.5-fold higher
Absolute Event Rate: 16.11% vs 2.16%
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).
Mark K Arness (Tue,) conducted a observational in Myopericarditis (n=492,730). Smallpox vaccination (Dryvax) vs. Nonvaccinated, active-duty military personnel was evaluated on Incidence of myopericarditis (7.5-fold higher). Primary smallpox vaccination with the Dryvax strain was associated with a nearly 7.5-fold higher incidence of myopericarditis (16.11/100,000) compared to the expected background rate (2.16/100,000).