Infant Pertussis and Household Transmission in Korea

Kwon, Hyo Jin; Yum, Sook Kyung; Choi, Ui Yoon; Lee, Soo Young; Kim, Jong Hyun; Kang, Jin Han

A resurgence of reported pertussis has been documented in a number of countries with high vaccine coverage since the 1990s (1, 4, 18) . DTaP vaccination coverage in Korea is very high, with 94% of the children completing the primary series of pertussis immunization. Despite the nationwide vaccination program with high coverage, the incidence of reported pertussis has continued to increase from 2000. Understanding the epidemiological and clinical features of pertussis in community is important because it remains a major cause of morbidity and mortality worldwide. In this study, we have made the demographic data from confirmed pertussis in an attempt to compare the clinical outcomes according to DTaP immunization. Generally, pertussis mostly occurred in young infants under 6 months of age who did not complete the primary series of DTaP vaccination. Depending on the immunization status of our patients, there were significant differences in clinical outcome similar to other studies (11, 19, 20) . The duration of hospital stay was significantly longer; and the severe cases admitted to ICU were found in patients without pertussis vaccination as compared to those with vaccination. The absolute lymphocytosis in laboratory findings was shown primarily in patients without the vaccination history. The main presenting symptom in typical pertussis is whooping cough. Even though all patients had paroxysmal cough for more than 1 week, whooping cough was present in only 14.3% of the patients. In addition, most patients showed no specific findings in chest radiographs. Because the presenting symptoms may be nonspecific, it is important for clinicians to suspect pertussis when there is prolonged cough or absolute lymphocytosis, especially in young infants with no or incomplete DTaP vaccination.