Chickenpox attributable to a vaccine virus contracted from a vaccinee withzoster

Five months after 2 siblings were immunized with varicella vaccine, 1 devel oped zoster. Two weeks later the second sibling got a mild case of chicken pox. Virus isolated from the latter was found to be vaccine type. Thus, the vaccine strain was transmitted from the vaccinee with zoster to his siblin g. Vaccinees who later develop zoster must be considered contagious.