Analysis of cases reported as generalized vaccinia during the US military smallpox vaccination program, December 2002 to December 2004

Abstract

We evaluated military personnel who developed dermatologic reactions suggestive of generalized vaccinia (GV) after smallpox vaccination. We conducted surveillance and retrospective analysis of cases from the Vaccine Adverse Event Reporting System (a passive reporting system managed by the Centers for Disease Control and Prevention), and the military's preventive medicine channels, vaccine healthcare centers, clinical laboratory network, dermatology clinics, and pathology departments from December 2002 to December 2004. Of 74 cases investigated in 753,226 vaccinations, 50 (67.6%) met the case definition of possible GV (rate 66/million), 95% confidence interval (49-88/million), consistent with historically reported rates. Cases of possible GV occurred more frequently in primary vaccinees (81/million) than in those revaccinated (32/million) (relative risk 2.6, 95% confidence interval 1.2-5.9, P = .013). None met the case definition of probable or confirmed GV, including 15 with virologically negative laboratory evaluations (eg, culture, skin biopsy, or polymerase chain reaction). The methods of case collection and retrospective nature of this study are its limitations. The clinical diagnosis of possible GV was made on the basis of the authors' interpretation of clinical notes and adverse events submitted by more than 100 different providers. Only 15 of the 74 cases of possible GV had laboratory attempts for virological confirmation. GV is still a rarely reported complication of smallpox vaccination. True GV, strictly defined, may be even less common than previously reported. We named one self-limited dermatologic manifestation confused with GV "postvaccinial nonviral pustulosis." Properly screened individuals considering smallpox vaccination may be assured most exanthemata after vaccination are benign.