Special Drug Use Investigation for VALTREX (Valaciclovir) (Pediatrics Chickenpox)

A serious adverse event is defined as any untoward medical occurrence that, at any dose, results in death, is life threatening, requires hospitalization or results in prolongation of existing hospitalization, results in disability/incapacity, or is a congenital anomaly/birth defect. For a list of all serious adverse events occurring during the course of the study, please see the table entitled "Serious Adverse Events" in the Adverse Event section of the results record.

An adverse drug reaction (ADR) is an adverse event whose causal relationship to study drug was not ruled out by the reporting physician. An adverse event is any untoward medical occurrence in a participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. For a list of all ADRs occurring during the course of the study, please also see the table entitled "Other (non-serious) adverse events" in the Adverse Event section of the results record.

An unexpected adverse drug reaction is an adverse event whose casual relationship to the study drug is not ruled out by the reporting physician and also is not listed in a package insert of the drug.

The course of symptoms was comprehensively assessed by the investigator on a four-category scale (Improved, Unchanged, Worsen, and Unassessable) before and after the initiation of valaciclovir therapy. "Improved" was regarded as "Effective," and "Unchanged" and " Worsen" were regarded as "Not effective." The two participants classifed as "Not effective" were classified as "Unchanged."