Elsevier

Vaccine

Volume 23, Issue 12, 10 February 2005, Pages 1434-1436
Vaccine

Seroprevalence of varicella antibodies in healthcare workers and health sciences students: Reliability of self-reported history of varicella

https://doi.org/10.1016/j.vaccine.2004.10.003Get rights and content

Abstract

The objective of this study was to assess the seroprevalence of varicella antibodies in healthcare workers and students of healthcare professions and to determine the validity of the self-reported varicella history for detecting susceptible subjects. Personnel of a general hospital and students were recruited and a 5 mL blood sample was obtained from all participants. A case report form, including previous self-reported history of varicella, was completed. A total of 91 healthcare workers (mean age, 30.6 years; S.D., 4.0; range, 23–40) and 92 students (mean age, 19.8 years; S.D., 2.5; range, 18–25) were recruited. The prevalence of varicella antibodies was 91.2% in healthcare workers and 92.1% in students. Overall, the sensitivity, specificity, positive and negative predictive values of a self-reported history of varicella were 68.4%, 66.7%, 95.4% and 17.2%, respectively. The preferred approach in these groups at risk of varicella will be to undergo serologic testing before immunization in those with negative or unknown history of varicella.

Introduction

Varicella, usually a benign disease, is associated with serious complications in both previously healthy and inmunocompromised persons [1], [2]. In developed countries, most cases occur in children, leading to high levels of immunity among adults. However, susceptible adults have a higher risk of severe disease and complications [3]. Age-specific seroprevalence describe the dynamics of primary varicella in the population and show the proportion of individuals remaining susceptible at a given age [4]. Healthcare workers may have a higher risk of exposure to varicella due to possible contact with cases [2]. Thus, susceptible healthcare workers and health sciences students are at increased risk of infection and, if infected, can expose susceptible patients to risk. Airborne nosocomial transmission of varicella-zoster virus (VZV) has been previously reported and existing guidelines recommend that all healthcare workers should ensure their immune status to varicella [2], [5].

Antibody testing is the most accurate way to show susceptibility to infection. However, systematic testing before immunization will not be the most appropriate strategy for economic and logistic reasons. Because the varicella-related rash is distinctive, a reliable history of varicella could be a valid method for detecting susceptible individuals [6]. This is of particular importance within groups of population at risk of exposure and transmission, as healthcare workers [7]. The objective of this study was to assess the seroprevalence of varicella in hospital healthcare workers and health science students and to determine the reliability of the self-reported history of varicella to detect susceptible subjects.

Section snippets

Study population

Healthcare workers were recruited from the University General Hospital 12 de Octubre in Madrid, Spain. University students in hospital training were recruited on a voluntary basis from the School of Health Sciences of the University Rey Juan Carlos in Madrid, Spain. All subjects were informed about the study rationale and objectives, and were asked to sign an informed consent form. Subjects were excluded if they had a history of varicella vaccination or had received immunoglobulin in the

Results

Between March and August 2003, a total of 91 healthcare workers and 92 students were included in the study. Mean age of the healthcare workers and students was 30.6 years (S.D., 4.0; range 23–40) and 19.8 years (S.D., 2.5; range, 18–25), respectively. Eighty-seven percent of the total study population were females. Three students were excluded because of an insufficient amount of serum was collected for analysis. The overall prevalence of varicella was 91.2% (83/91) (95% CI, 83.4%–96.1%) in

Discussion

An increase in the susceptibility to varicella among teenagers and young adults has been reported in some developed countries [11], [12], [13]. The epidemiological pattern of VZV infections should be reviewed periodically for evidence of a shift in the age of contact with VZV that could be associated to an increased proportion of susceptible adults, which may imply an increase of varicella-associated complications [11], [12]. Our study shows that 9% of healthcare workers in a public hospital

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