Varicella Vaccine (VarilRix) in Children with Acute Lymphoblastic Leukemia.

Background: To assess the effectiveness of vaccination against varicella in children with acute lymphoblastic leukemia (ALL).

Methods: 105 children without a history of varicella, were qualified for immunization against varicella with VARILRIX (Oka-strain varicella vaccine). 48 children had ALL and 57 were healthy. 25 of the children with ALL were receiving maintenance therapy, 23 children were after chemotherapy.

Results: White blood cells (WBC), lymphocytes, and sub-populations of T- and B-lymphocytes were compared in the healthy and leukemic children before and after vaccination. The ALL children had significantly lower counts of WBC and lymphocytes before vaccination. After vaccination there were no significant differences in the counts of WBC in the healthy and leukemic children. However the ALL children had significantly lower mean counts of lymphocytes. Before vaccination the leukemic children showed a significantly lowered percentage of T-lymphocytes with decreased CD4+ and increased CD8+, what resulted in a lowered CD4 to CD8 ratio. After vaccination, only increased numbers of T CD8+ lymphocytes and a lowered CD4 to CD8 ratio were present while there was no significant difference in CD4. In the healthy and leukemic children alike there was no statistically significant difference between B-lymphocytes (CD 19+) and NK cells.

In 10 children (20%), out of the 48 ALL vaccines, varicelliform rash occurred ~1 month after immunization. No adverse effects we observed in healthy children. Seroconversion to varicella-zoster virus was higher in healthy children and ALL children who had skin rash after vaccination. Two ALL children and three healthy ones had varicella one-two years after the vaccination. Those children received only single vaccine doses (double vaccine doses received children above 12 years).

Conclusion: Varicella vaccine was safe and immunogenic in leukemic children during maintenance and after chemotherapy.