Persistence of immunity to varicella-zoster virus after vaccination of healthcare workers.
OBJECTIVE
Varicella-zoster virus (VZV) vaccine is recommended to protect susceptible healthcare workers (HCWs) from serious disease and to prevent nosocomial spread of VZV. We evaluated clinical outcomes and serological responses in HCWs after immunization with live attenuated VZV vaccine.


METHODS
Vaccinees were immunized from 1979 to 1998 during VZV vaccine trials, as well as after licensure, and followed prospectively for 1 month to 20.6 (mean 4.6) years after vaccination. Sera were tested by fluorescent antibody to membrane antigen (FAMA), latex agglutination (LA), and enzyme-linked immunoassay (EIA) to detect VZV-specific antibodies.


METHODS
The median age of the 120 HCWs was 26 years; 51 (42%) were males.


METHODS
Ninety eight (82%) of these study subjects received vaccine prepared by Merck and 22 (18%) by SmithKline Beecham; 25, 81, and 14 vaccinees received one dose, two doses, and three doses, respectively.


RESULTS
The crude attack rate was 10%; 12 of 120 HCWs developed chickenpox 6 months to 8.4 years after vaccination. The attack rates following household and hospital exposures were 18% (4/22) and 8% (6/72), respectively. All resulting illness was mild to moderate (mean 40 vesicles). Seroconversion after vaccination was documented by FAMA in 96% of HCWs, although 31% lost detectable antibodies. Compared with FAMA, LA and EIA were 82% and 74% sensitive and 94% and 89% specific, respectively.


CONCLUSIONS
The VZV vaccine effectively protected HCWs from varicella, particularly from serious disease. Currently available serological tests are not optimal, and improved assays are needed.
Saiman
L
L
Department of Pediatrics, Columbia University, College of Phyicians & Surgeons, New York City, New York 10032, USA.
LaRussa
P
P
Steinberg
S P
SP
Zhou
J
J
Baron
K
K
Whittier
S
S
Della-Latta
P
P
Gershon
A A
AA
D000914:Antibodies, Viral / Q000097:blood*; D016009:Chi-Square Distribution; D002644:Chickenpox / Q000517:prevention & control*; D019433:Chickenpox Vaccine / Q000008:administration & dosage / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006282:Health Personnel; D014645:Herpesvirus 3, Human / Q000276:immunology*; D006801:Humans; D017589:Immunization Programs; D007841:Latex Fixation Tests; D008297:Male; D011446:Prospective Studies; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology
D000914:Antibodies, Viral; D019433:Chickenpox Vaccine; D014613:Vaccines, Attenuated