Passive immunization against varicella in sick neonates by transfusion from donors immunologically enhanced by previous vaccination with live varicella vaccine.

Twenty-six sick children in a neonatal unit received passive immunization against varicella shortly after close contact with varicella in the ward, with the aim of preventing nosocomial infection. Because zoster immune globulin was not available at the time, the babies were given transfusion of whole blood from donors. All these donors had a history of varicella in childhood, and had received live varicella vaccine, Oka strain, to increase their immunological status before use of their blood for transfusion. Only one of the recipients contracted varicella after the passive immunization. No adverse reaction attributable to the transfusion was observed.