Varicella seroprevalence among health care workers in Korea: validity of self-reported history and cost-effectiveness of prevaccination screening.

BACKGROUND

The validity of self-reported varicella history and cost-effectiveness of a prevaccination screening strategy have not been examined among health care workers (HCWs) living in Korea.

METHODS

We investigated varicella-zoster virus immunity of all HCWs in high-risk departments. To determine the history of varicella, all applicants completed a standardized questionnaire at the time of blood sampling for serologic testing.

RESULTS

Of the 550 HCWs, 526 (96%) were varicella seropositive. Although self-reported history was highly predictive of seropositivity (≥96%) among all age groups, the negative predictive value was extremely low (4%-5%) among all age groups. The prevaccination screening strategy was cheaper than vaccination without antibody screening if the varicella seroprevalence was >28%.

CONCLUSION

Seroprevalence was high (≥95%) among HCWs born in Korea before 1988. The self-reported varicella history did not accurately predict immunity, especially for individuals who have negative or uncertain varicella history. Given the high seroprevalence of varicella in Korean HCWs, serologic screening before vaccination was more cost-effective than universal vaccination.