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

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.