Aplastic anemia following varicella vaccine.

Varicella zoster vaccine is a safe vaccine that is rarely associated with life-threatening complications. We describe an immunocompetent child who developed transient severe aplastic anemia concomitant with a typical clinical and laboratory-proven chickenpox syndrome 3 weeks after immunization. A causative association between the vaccine and the hematologic disease is possible, and pediatricians should be aware of this severe although rare adverse event.