Management of varicella exposure in a neonatal intensive care unit

We describe the management of an exposure to varicella in a neonatal intensive care unit. Thirty-seven hospital staff members with negative histories of varicella were tested by enzyme-linked immunosorbent assay for antibody to varicella zoster; all were seropositive. None were restricted from clinical duties, were given varicella-zoster immune globulin, or developed disease. Although only 1 of 38 cord serum samples from normal term infants was seronegative, 10 of 22 neonatal intensive care unit infants were seronegative. The high rate of seronegativity among these patients was related to chronological age older than 2 months and to multiple transfusions of packed red blood cells. This probably reflects natural catabolism of maternal antibody and loss of antibody in serum removed from these infants for diagnostic tests. Infants lacking antibody were given varicella-zoster immune globulin. Antibody levels following administration of varicella-zoster immune globulin were directly related to the dose administered.