Mass psychogenic illness following oral cholera immunization in Ca Mau City, Vietnam.

Introduction: Targeted cholera immunization of high-risk populations in Vietnam is conducted based on routine surveillance data. Following mass immunization of schoolchildren in Ca Mau City using an oral bivalent killed cholera vaccine, adverse reactions were noted.

Methods: Salient data were collected in a systematic fashion including the review of medical records; interview of the school principal, teachers, students, parents and doctors; and review of the storage and handling of the vaccine.