Sudden Infant Death After Vaccination: Survey of Forensic Autopsy Files.

Sudden infant deaths might be attributable to adverse reaction to vaccination, but separating them from coincidental occurrences is difficult. This study retrospectively investigated vaccination-related details and postmortem findings for 57 cases of sudden death in children 2 years or younger. Data were extracted from autopsy files at the Department of Forensic Medicine, Tokai University School of Medicine. Vaccination histories were available in 50 cases based on the maternity passbook. Of the 32 cases in which any vaccines were administered, 7 infants (21.9%) had received immunization within 7 days of death. The most frequent vaccine cited as the last immunization before death was Haemophilus influenzae B. Although a temporal association of vaccines with sudden death was present for two 3-month-old and one 14-month-old infants in whom death occurred within 3 days of receiving the H. influenzae type b and other vaccinations, a definitive relationship between the vaccine and death could not be identified. Histopathological examinations revealed pneumonia and upper respiratory infection as contributing to death in their cases. Moreover, all 3 cases showed hemophagocytosis in the spleen and lymph nodes, which are similar features to hemophagocytic lymphohistiocytosis. Judgment of the disorders as truly related to vaccination is difficult, but suspicious cases do exist. Forensic pathologists must devote more attention to vaccination in sudden infant death cases.