Varicella-zoster virus immunity among health care workers in Catalonia

To determine varicella-zoster virus (VZV) immunity among healthcare workers (HCWs). Cross-sectional study.

HCWs attending voluntary periodic health examinations between June 2008 and December 2010.

Six public hospitals and five primary care areas in Catalonia, Spain.

A self-administered questionnaire was given to eligible HCWs. Variables including age, sex, professional category, type of centre, history of varicella infection, and VZV vaccination were collected. The study was carried out using a convenience sample. The prevalence of antibodies and positive and negative predictive values (PPV and NPV) of the history of clinical VZV infection or vaccination were calculated. Crude and adjusted odds ratios (OR and ORa) and their 95% confidence intervals (CI) were calculated to determine the variables associated with antibody prevalence.

Of 705 HCWs who agreed to participate, 644 were finally included. The overall prevalence of antibodies to varicella was 94.9% (95% CI: 92.9-96.4). Of the variables studied, only age was associated with serological susceptibility to VZV. HCWs aged 25-35 years had the highest serological susceptibility (8.1%, 95% CI: 4.6-13.0). The prevalence of antibodies was 96% in subjects reporting previous VZV infection or vaccination, compared with 93% in subjects who did not report these states or did not know.

The high proportion of serologically-susceptible HCWs found in this study indicates the need to develop for screening and vaccination strategies in Catalonia. Due to the high capacity of propagation of the VZV in health settings and its consequences, VZV vaccination programmes in HCWs should be reinforced.