Prevention or Modification of Varicella Using Zoster Immune Plasma

Zoster immune plasma (ZIP) was given to 31 susceptible immunocompromised children one to seven days (median, two days) following household, playmate, or hospital exposures to varicella. The average amount of ZIP transfused was 7 ml/kg. Twenty-one children did not develop varicella or persistent antibodies to varicella-zoster virus (VZV). Eight (26%) of the 31 contracted clinical varicella. Seven cases were mild, but in one child, who was given ZIP seven days after exposure, visceral disease developed and the child died. Two children had subclinical varicella that was documented by persistence of VZV antibodies for at least ten months after passive immunization. Because none of the 30 children given ZIP one to six days following exposure had severe varicella, we conclude that ZIP is effective in preventing or modifying varicella in immunocompromised patients if given shortly after exposure.