Seroprevalence of pertussis in healthcare workers without adult pertussis vaccine use at a university hospital in Korea

Background: Pertussis is highly contagious respiratory disease. Healthcare workers (HCWs) can be an important mediator of the disease. A seroprevalence of pertussis was investigated in HCWs to determine the immune status against pertussis and to detect the unidentified pertussis. Methods: This study was conducted for HCWs at a hospital located in Korea in 2011. After obtaining written informed consent for HCWs voluntarily participating in the study, 10 mL of blood was collected from each subject. Demographic and medical data were collected using questionnaire. Data on the underlying disease and vaccination history were reviewed again through medical records. The presence of anti-pertussis toxin (anti-PT) immunoglobulin G (IgG), and immunoglobulin A (IgA) was detected by quantitative analysis using a commercially available ELISA kit (EUROIMMUN, Lübeck, Germany). Results: A total of 412 HCW participated in the study. Among them, 14 were excluded due to the inadequate sample amount or medical history not secured. Of the 398 HCWs analyzed, 16.6% (66/398) were men and the mean age was 33.82 ± 9.10 years (range, 21-67). The mean anti-PT IgG titer was 8.32 ± 20.40 IU/mL (range, 0.4-287.5 IU/mL). The overall seroprevalence (rate of anti-PT IgG antibody [Ab] titer > 5 IU/mL) was 33.7%. Three (0.8%) HCWs had the Ab level > 100 IU/mL indicated acute infection. There was no statistically significant difference in the seroprevalence and mean titer of anti-PT IgG Ab according to age group, type of occupation, patient-facing position, or working in the pediatric department. Conclusion: The seroprevalence of pertussis of the HCWs of a university hospital in Korea was low, and there were some unrecognized acute infections. Therefore, booster immunization of pertussis to HCWs should be actively considered.