Reliability of self-reported history in predicting immunity against measles, rubella, mumps, and varicella among health care workers.

Aim: To determine the immunity of health care workers (HCWs) against measles, rubella, mumps, and varicella infections, and to evaluate the reliability of self-reported history of the disease in predicting immunity. Materials and methods: A self-reported questionnaire was used to obtain the history of the diseases and ELISA to screen specific IgG antibodies. The history of the diseases was compared with serological testing results. Results: Eighty-one HCWs were included in the study. Immunity against measles was 97.5%, rubella 100%, mumps 72.8%, and varicella 96.3%. Positive predictive values of positive histories of the diseases were 100% for measles and rubella, 96.5% for varicella, and 77.4% for mumps. The negative predictive values of the negative/unknown histories were 3.9%, 0%, 3.8%, and 30.0% for measles, rubella, varicella, and mumps, respectively. Conclusion: A positive history of the disease is reliable for predicting the immunity against measles, rubella, and varicella, and vaccination is not required for the HCWs with a positive history. In contrast, a negative/unknown history had no benefit in predicting susceptibility; thus, we consider that these HCWs must be vaccinated according to the serological testing results. For mumps, a decision for vaccination of HCWs can be made by combining the self-reported history and serological testing results.