Introduction Autoimmune allergic reaction causing myopericarditis following vaccination is extremely rare and, in this regard, much attention has been paid to smallpox vaccine. Halsell et al., reported 18 cases of probable myopericarditis in 230,734 primary vaccines after smallpox vaccination (an incidence of 7.8 per 100,000 over 30 days). No cases of myopericarditis following smallpox vaccination were reported among 95,622 vaccines who were previously vaccinated. A causal relationship was supported by the close temporal clustering (7-19 days; mean, 10.5 days following […]