[Susceptibility to varicella among health care workers. Acceptability and response to vaccination]

Abstract

Background and objective: To determine the prevalence of health care workers (HCW) susceptibility to varicella zoster virus (VZV). As a secondary objective, we describe the immunogenicity and reactogenicity of the vaccine.

Subjects and methods: A multicenter analytic cross-sectional study was conducted in 5 hospitals in Catalonia, Spain, in a total of 1,111 HCW, aged between 18-60 years. We studied the prevalence of anti-VZV antibodies (IgG) and obtained demographic, occupational and health related variables that were expected to be associated with immunogenicity, as well as past history of varicella. All susceptible HCW were vaccinated and we studied the immunogenicity (antibody detection) and reactogenicity of the 1st and 2nd doses of the vaccine. Detection of antibodies against VZV was obtained by ELISA. All negative results were confirmed with FAMA.

Results: Forty two subjects (3.8%) were negative. Susceptibility to VZV was associated (p<0.05) with decreased age (29.6 years ± 8.5 vs. 32,5 ± 9,3 in non-susceptible individuals), having fewer siblings and having no previous clinical history of varicella. Postvaccination detection tests with ELISA showed a seroconversion rate of 52 and 86% after the 1st and 2nd doses of the vaccine respectively, and 100% when using FAMA. There were no significant adverse events.

Conclusions: Susceptibility to varicella among HCW is low. Positive past history of varicella is a good predictor of previous exposure to VZV, since 99% (687/696) of the individuals that declared having experienced the disease were immune. This would avoid prevaccination screening in nearly two thirds of HCW.