Chickenpox in varicella IgG positive patients: experience of a regional paediatric oncology centre.

Aciclovir prophylaxis was previously given to all immunocompromised patients treated by our unit, following contact with varicella zoster. In 2003, we changed practice according to National Guidelines, giving prophylaxis only to patients without serum varicella zoster immunoglobulin G antibody (VZ IgG) at diagnosis of their malignancy. Since then we have seen nine patients with acute lymphoblastic leukaemia (ALL) and VZ IgG positivity at diagnosis of their malignancy develop chickenpox. Our observations question current practice for patients with ALL.