VARICELLA VACCINE - WHO IS CONCERNED

A live-attenuated varicella vaccine was first developed in the 70's in Japan by Takahashi from the attenuated Oka strain of varicella-zoster virus (VZV). In immunocompromised children, i.e., children with leuke mia or solid malignant tumour, 2 doses of vaccine titered greater than or equal to 2000 plaque forming units (PFU), injected subcutaneously 3 months apart, provide 100 % seroconversion with persistence of anti- VZV-antibodies for at least one year. Protective efficacy after exposu re to a varicella case is estimated between 83 and 87.5 %. 15 to 20 % of vaccinated children show mild and transient post-vaccine eruptions. One single dose of varicella vaccine of the same titer is needed in i mmunocompetent children but two doses are recommended in adults. Recur rence of VZV, causing herpes-tester in adulthood, might be prevented b y stimulating the host immune system with the varicella vaccine.