Seroprevalence of varicella antibodies in healthcare workers and health sciences students: Reliability of self-reported 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.
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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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2013, American Journal of Infection ControlCitation Excerpt :The low response rate (36.4%) and estimation of susceptibility rates based on self-reported questionnaires constitute potential limitations; however, our results are in accordance with those reported in a previous study of hospitals in Greece.28 In addition, previous studies have reported a positive predictive value of >93% for immunity against measles, rubella, varicella, and hepatitis B vaccination.17,33,40,41 In conclusion, although two-thirds of HCWs working in primary health care centers in Greece support mandatory vaccinations for HCWs, self-reported completed vaccination rates are suboptimal.