The efficacy of
zoster immunoglobulin (ZIG) in preventing
varicella was studied among patients in a high-risk group. 173 non-immune patients were observed after exposure to
varicella-
zoster (VZ) virus and subsequent administration of ZIG. For 138 patients (80%) no sign of
varicella was recorded, 16 patients (9%) had a
subclinical infection and 19 patients (11%) developed
varicella. 12/19 patients with
varicella contracted a very mild disease (less than 20 pocks, negligible
fever), 5 got mild or normal disease and 2 children, both with acute lymphatic
leukemia, developed more pronounced symptoms. Three patients protected by 0.15 ml ZIG/kg
body weight after heavy exposure to VZ virus, were not protected at a second exposure 2 weeks later. In an enlarged study group of high-risk patients where 52 patients receiving ZIG developed
varicella, the mean incubation period for 42 patients was 21 days. Leukemic patients were found to have a higher frequency of clinical
varicella, more pronounced symptoms and a slightly longer incubation period than other high-risk patients. VZ specific antibody titers were compared for various
immunoglobulin preparations and found to be 30 times higher in
zoster immunoglobulins than in normal
immunoglobulins.