Usefulness and Limitations of PFGE Diagnosis and Nucleotide Sequencing Method in the Analysis of Food Poisoning Pathogens Found in Cooking Employees.

In the case of a food poisoning outbreak, it is essential to understand the relationship between cooking workers and food poisoning. Many biological diagnostic methods have recently been developed to detect food poisoning pathogens. Among these diagnostic tools, this study presents PCR-based pulsed-field gel electrophoresis and nucleotide sequencing diagnostic analysis results for diagnosing food poisoning outbreaks associated with cooking employees in Chungcheongnam-do, Republic of Korea. Pulsed-field gel electrophoresis was useful in identifying the food poisoning outbreaks caused by Staphylococcus aureus and Enteropathogenic Escherichia coli. In the case of Norovirus, nucleotide sequencing was used to identify the relationship between cooking workers and the food poisoning outbreak. However, it is difficult to determine whether cooking employees directly caused the food poisoning outbreaks based on these molecular biological diagnostic results alone. A system is needed to integrate epidemiological and diagnostic information to identify a direct correlation between the food poisoning outbreak and cooking employees.

Validity of Rapid Antibody Testing for COVID-19 Vaccine in Homeless People.

(1) Background: There is a paucity of data regarding the validity of rapid antibody testing for SARS-CoV-2 vaccine response in homeless people worldwide. The objective of this study was to evaluate a rapid SARS-CoV-2 IgM/IgG antibody detection kit as a qualitative screen for vaccination in homeless people. (2) Methods: This study included 430 homeless people and 120 facility workers who had received one of BNT162b2, mRNA-1273, AZD1222/ChAdOx1, or JNJ-78436735/AD26.COV2.5 vaccines. They were tested for IgM/IgG antibodies to the SARS-CoV-2 spike protein with the STANDARD™ Q COVID-19 IgM/IgG Plus Test (QNCOV-02C). ELISA/competitive inhibition ELISA (CI-ELISA) was subsequently run to assess the validity of the serological antibody test. (3) Results: The sensitivity of homeless people was 43.5%. The status of homelessness was related to a lower agreement between serological antibody testing and CI-ELISA (adjusted OR (aOR), 0.35; 95% CI, 0.18-0.70). However, the Heterologous boost vaccine presented higher agreement between serological antibody testing and CI-ELISA (adjusted OR (aOR), 6.50; 95% CI, 3.19-13.27). (4) Conclusions: This study found weak agreement between the rapid IgG results and confirmatory CI-ELISA testing in homeless people. However, it can be used as a screening test for the acceptance of homeless people with heterologous boost vaccination in facilities.

The impact of the COVID-19 pandemic on chlamydia infection in South Korea: a comparison between the pre-pandemic and during-pandemic periods.

Background: Prior to COVID-19 pandemic, a yearly upward trajectory in the number of chlamydia infection cases was observed in South Korea. However, in response to the COVID-19 pandemic, Korea implemented several public health and social measures, which were shown to have an impact on the epidemiology of other infectious diseases. This study aimed to estimate the impact of the COVID-19 pandemic on the incidence and number of reported chlamydia infections in South Korea. Methods: Using the monthly number of reported chlamydia infection data between 2017 and 2022, we compared the trends in the reported numbers, and the incidence rates (IR) of chlamydia infection stratified by demographic characteristics (sex, age group, and region) in the pre- and during COVID-19 pandemic period (January 2017-December 2019 and January 2020-December 2022). Results: We observed an irregular downward trajectory in the number of chlamydia infection in the during-pandemic period. A 30% decrease in the total number of chlamydia infection was estimated in the during-pandemic compared to the pre-pandemic period, with the decrease greater among males (35%) than females (25%). In addition, there was a decrease in the cumulative incidence rate of the during COVID-19 pandemic period (IR: 0.43; 95% CI: 0.42-0.44) compared to the pre-pandemic period (IR: 0.60; 95% CI: 0.59-0.61). Conclusions: We identified decrease in the number of chlamydia infection during COVID-19 pandemic which is likely due to underdiagnosis and underreporting for the infection. Therefore, strengthening surveillance for sexually transmitted infections including chlamydia is warranted for an effective and timely response in case of an unexpected rebound in the number of the infections.

Diagnostic Laboratory Characteristics of COVID-19 Patients Infected by Fomites: COVID-19 Outbreak in a South Korean Public Administrative Facility.

There is a paucity of data regarding the differentiating characteristics of patients who were infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) by fomites around the world. We conducted an event-based outbreak investigation, involving 795 public officers and 277 assistant staff, in the Ministry of Oceans and Fisheries (MOF) or the same building from March 2 to March 18, 2020. The SARS-CoV-2 patients were found to have more frequently touched fomites and used public toilets than those who were tested negative for the virus (cOR, 24.38; 95% CI, 4.95-120.01). Symptoms such as coughing and loss of taste and smell were more frequently found in the office-cleaner group than in the public-officer group. The SARS-CoV-2 office-cleaner patients were more likely to have a high RdRp(Ct) value of PCR (median: 34.17 vs. 24.99; p = 0.035) and E(Ct) value of PCR (median: 32.30 vs. 24.74; p = 0.045). All office cleaner patients (100%) had a ground glass opacity in both lobes. Regarding segmental lung involvement of CT, two patients (100%) had a lesion in the right middle lobe, which invaded the whole lobe later. This implies that the fomite might be a selective risk factor of SARS-CoV-2 infection.

Clinical and Laboratory Findings of Middle East Respiratory Syndrome Coronavirus Infection.

There is a paucity of data regarding the differentiating characteristics of patients with laboratory-confirmed and those negative for Middle East respiratory syndrome coronavirus (MERS-CoV) in South Korea. This hospital-based retrospective study compared MERS-CoV-positive and MERS-CoV-negative patients. A total of seven positive patients and 55 negative patients with a median age of 43 years (P = 0.845) were included. No statistical differences were observed with respect to their sex and the presence of comorbidities. At the time of admission, headache (28.6% vs. 3.6%; odds ratio [OR], 10.60; 95% confidence interval [CI], 1.22-92.27), myalgia (57.1% vs. 9.1%; OR, 13.33; 95% CI, 2.30-77.24), and diarrhea (57.1% vs. 14.5%; OR, 7.83; 95% CI, 1.47-41.79) were common among MERS-CoV-positive patients. MERS-CoV-positive patients were more likely to have a low platelet count (164 ± 76.57 vs. 240 ± 79.87) and eosinophil (0.27 ± 0.43 vs. 2.13 ± 2.01; P = 0.003). Chest radiography with diffuse bronchopneumonia was more frequent in MERS-CoV-positive patients than in negative patients (100% vs. 62.5%; P = 0.491). The symptoms of headache, myalgia, and diarrhea, as well as laboratory characteristics, including low platelet counts and eosinophil, and chest X-ray showing diffuse bronchopneumonia might enhance the ability to detect patients in South Korea infected with MERS-CoV.

Assessing the impact of meteorological factors on malaria patients in demilitarized zones in Republic of Korea.

BACKGROUND: The trend of military patients becoming infected with vivax malaria reemerged in the Republic of Korea (ROK) in 1993. The common explanation has been that infective Anopheles mosquitoes from the Democratic People's Republic of Korea have invaded Republic of Korea's demilitarized zone (DMZ). The aim of this study was to verify the relationship between meteorological factors and the number of malaria patients in the military in this region. METHODS: The authors estimated the effects of meteorological factors on vivax malaria patients from the military based on the monthly number of malaria cases between 2006 and 2011. Temperature, precipitation, snow depth, wind velocity, relative humidity, duration of sunshine, and cloud cover were selected as the meteorological factors to be studied. A systematic pattern in the spatial distribution of malaria cases was assessed using the Moran's Index. Granger causality tests and cross-correlation coefficients were used to evaluate the relationship between meteorological factors and malaria patients in the military. RESULTS: Spatial analysis revealed significant clusters of malaria patients in the military in Republic of Korea in 2011 (Moran's I = 0.136, p-value = 0.026). In the six years investigated, the number of malaria patients in the military in Paju decreased, but the number of malaria patients in the military in Hwacheon and Chuncheon increased. Monthly average, maximum and minimum temperatures; wind velocity; and relative humidity were found to be predicting factors of malaria in patients in the military in Paju. In contrast, wind velocity alone was not able to predict malaria in Hwacheon and Chuncheon, however, precipitation and cloud cover were able to predict malaria in Hwacheon and Chuncheon. CONCLUSIONS: This study demonstrated that the number of malaria patients in the military is correlated with meteorological factors. The variation in occurrence of malaria cases was principally attributed to differences in meteorological factors by regions of Republic of Korea.

Predictors of job satisfaction and burnout among tuberculosis management nurses and physicians.

OBJECTIVES: This study examined job satisfaction, empowerment, job stress, and burnout among tuberculosis management nurses and physicians in public healthcare institutions. METHODS: This was a cross-sectional study analyzing survey data collected from 249 nurses and 57 physicians in 105 public health centers, three public tuberculosis hospitals, and one tertiary hospital. The survey questionnaire comprised general characteristics, work-related characteristics, and four index scales (job satisfaction, empowerment, job stress, and burnout). The two-sample t-test was used to estimate the mean differences in the four index scales. Multiple regression analysis was used to determine whether general and work-related characteristics affected the four index scales. RESULTS: The job satisfaction and empowerment scores of the nurses were lower than those of the physicians. Except for the tuberculosis-specialized hospitals alone, the average job satisfaction scores of nurses were higher than those of physicians. Moreover, the nurses reported more job stress and burnout than did the physicians in tuberculosis departments in public healthcare institutions in Korea; in particular, the burnout reported by nurses was significantly higher than that reported by physicians at the National Medical Center. Marital status, nursing position, number of coworkers, the average number of days of overtime work per month, self-rated health, and hospital type were associated with the four index scales. CONCLUSIONS: Overall, nurses were more vulnerable to job stress and burnout than physicians. Reducing the workload of nurses by ensuring the presence of sufficient nursing staff and equipment, as well as by equipping facilities to prevent tuberculosis infections, should be considered priorities.

Implementation and results of a survey on safe community programs in Gangbuk-gu, Korea: focusing on participants at a local public health center.

OBJECTIVES: The purpose of this study was to investigate the current status of and problems with the Safe Community Programs in Gangbuk-gu, one of the 25 districts of the capital city of Korea. METHODS: The study subjects were 396 individuals who were involved in Safe Community Programs between 2009 and 2011. We examined the effectiveness and willingness of respondents to participate as a safety leader of the Safe Community Program with a questionnaire. We examined the injury death rates of Gangbuk-gu by using of the death certificate data of Korea's National Statistical Office. Descriptive statistics and chi-squared tests were used. RESULTS: The effectiveness of programs did not differ but active participation differed significantly among subjects (p<0.05). The injury death rate of Gangbuk-gu as a whole increased during the implementation period. However, senior safety, in particular, may be a helpful program for reducing injuries in Gangbuk-gu. CONCLUSIONS: This study suggests that the lack of active participation may be a major problem of Safe Community Programs in Gangbuk-gu. Therefore, Safe Community Programs should be expanded to the entire district of Gangbuk-gu and more active participation programs should be developed.

Outbreak of febrile respiratory illness caused by adenovirus at a South Korean military training facility: clinical and radiological characteristics of adenovirus pneumonia.

Adenovirus often causes respiratory disease outbreaks in military training soldiers. Compared with adenovirus pneumonia in young military adults, symptoms arising from febrile respiratory illness (FRI) caused by adenovirus have not been previously evaluated in Korean soldiers. We conducted an event-based outbreak investigation involving 712 male soldiers aged 19 to 21 years from March 14 to 30, 2012 to evaluate the epidemiological and clinical characteristics of patients with pneumonia and FRI caused by adenovirus. We described the laboratory and radiological characteristics of patients with adenovirus pneumonia. Among these, 407 cases of FRI and 15 cases of pneumonia were identified through active surveillance (attack rate of FRI, 57.16%; attack rate of pneumonia, 2.11%). Fire training and march training may present environmental risk factors for adenovirus-associated outbreaks. Most symptoms were mild. The most frequent symptom in patients with pneumonia and FRI was cough. Patients with pneumonia were associated with an increased incidence of dizziness (crude odds ratio [cOR], 9.65; 95% confidence interval [CI], 2.38-37.15) and a decreased incidence of rhinorrhea (cOR, 0.15; 95% CI, 0.04-0.53) during adenovirus-associated outbreaks. Differential leukocyte count revealed high monocytes, low lymphocytes, and low eosinophils, and chest computed tomography revealed a consolidation pattern and right lobar pneumonia. These findings warrant a high level of suspicion for adenovirus pneumonia.

Usefulness of plasma epigenetic changes of five major genes involved in the pathogenesis of colorectal cancer.

PURPOSE: The purpose of present study was to investigate the methylation status of the promoter region in five genes (mothers against decapentaplegic homolog 4, fragile histidine triad protein, death-associated protein kinase 1, adenomatous polyposis coli (APC), and E-cadherin), which are known to be involved in the pathogenesis of colorectal cancer (CRC) and its clinicopathological significance. METHODS: The study subjects were 60 CRC patients, 40 patients with adenomatous colorectal polyp and 60 healthy control individuals. We further enrolled a total of 16 patients (two patients with Crohn's disease, two patients with ulcerative colitis, one patient with serrated adenoma, and 11 patients with colorectal cancer). The methylation states of the five genes were determined in peripheral blood plasma using methylation-specific polymerase chain reaction single-strand conformation polymorphism analysis. RESULTS: This study showed the most sensitive epigenetic markers, E-cadherin (60 %), followed by APC (57 %), for detecting CRC. E-cadherin and APC had similar specificities and amplified 84 and 86 %, respectively, of CRC patients compared to non-CRC patients. Additionally, APC was the only marker to be significantly increased (OR = 6.67, 95 % CI = 1.19-23.4, P = 0.045) and the most sensitive (57 %) and specific (89 %) marker in stage I CRC. Though we have not examined the paired cancer tissues and plasma, there was relatively high concordant rate (60-80 %) in our limited number of colorectal cancer patients. CONCLUSIONS: Five genes, promoter methylation, in plasma were statistically significant risk factors in CRC patients. In this study, E-cad and APC genes may be particularly useful epigenetic biomarkers in plasma for the detection of CRC. Additionally, APC may able to identify early potential CRC.

Comparison of the adverse events associated with MF59-adjuvanted and non-adjuvanted H1N1 vaccines in healthy young male Korean soldiers.

The first large-scale outbreaks of respiratory disease in the 21st century were caused by the influenza A (H1N1) virus in 2009, which affected mostly young adults. The M59 vaccine was developed to control pandemic influenza A (H1N1). However, the complications arising from the use of the non-adjuvanted and adjuvanted vaccines in young male Korean soldiers have not previously been evaluated and compared. We conducted a prospective multicenter study of 2,864 healthy male soldiers aged 19 to 25 years to evaluate the adverse events associated with both the MF59-adjuvanted and non-adjuvanted forms of the influenza A/California/2009 (H1N1) surface-antigen vaccine. In most cases, the adverse-event symptoms were mild, and the most frequent adverse events were swelling at the injection site and myalgia, which were noted in 4.8% and 10.7% of participants, respectively. Administration of the MF59-adjuvanted vaccine was associated with an increased incidence of local (crude odds ratio [cOR], 1.56; 95% confidence interval [CI], 1.11-2.29) and systemic adverse events (cOR, 1.64; 95% CI, 1.29-2.07) after vaccination. Atopic dermatitis (adjusted OR [aOR], 2.32; 95% CI, 0.99-5.46) might be the choice risk factor for local adverse events, and adjuvant use (aOR, 1.35; 95% CI, 1.03-1.78) was a significant predictor of systemic adverse events in healthy young male Korean soldiers.

The positive association between peripheral blood cell counts and bone mineral density in postmenopausal women.

PURPOSE: Accumulating evidence has shown a close connection between hematopoiesis and bone formation. Our aim was to evaluate the association between peripheral blood cell counts and bone mineral density (BMD) in a sample of postmenopausal women. MATERIALS AND METHODS: Three hundreds thirty eight healthy postmenopausal women who underwent BMD measurement during their health check-up were investigated. BMD was measured by dual energy X-ray asorptiometry at L1-L4 spine, femoral neck and total proximal femur. BMD was expressed as a T-score: among T-scores obtained from three different sites (L1-L4 spine, femoral neck and total proximal femur), the lowest T-score was considered to be the subject's T-score. RESULTS: The prevalence of osteopenia and osteoporosis diagnosed by T-score in the study participants were 49.4% (167/338) and 5.0% (17/338), respectively. Peripheral blood white blood cell (WBC), red blood cell (RBC) and platelet counts had significant positive correlations with T-scores (p<0.001) upon simple linear regression analysis. A multiple linear regression analysis, after controlling of confounders including age, body weight, systolic blood pressure, alkaline phosphatase and creatinine, showed that WBC (ß=0.127; standard error=0.043; p=0.014), RBC (ß=0.192; standard error=0.139; p<0.001) and platelet (ß=0.097; standard error=0.001; p=0.050) counts still had significant positive association with T-scores. CONCLUSION: The study results showed a positive relationship between blood cell counts and bone mineral density in postmenopausal women, supporting the idea of a close connection between hematopoiesis and bone formation. The study results also suggest that blood cell counts could be a putative marker for estimating BMD in postmenopausal women.

The adverse events of influenza A (H1N1) vaccination and its risk factors in healthcare personnel in 18 military healthcare units in Korea.

In this study, we characterized adverse events related to influenza A (H1N1) vaccination and studied the factors that influence the occurrence of these events. A total of 4,302 personnel in 18 military healthcare units in Korea received 0.5 ml of inactivated H1N1 vaccine. The study questionnaires were answered by 3,939 (91.6%) personnel, at both 2 weeks and 4 weeks after vaccination. Among these subjects, 3,531 (82.1%) who responded to all questions in the questionnaire were studied. After immunization, military doctors were ordered to report the occurrence of any adverse event related to the vaccine for 2 months. According to the responses of the subjects, the most prevalent events were fatigue (11.3%), pain at the injection site (8.38%), and myalgia (6.97%). Female gender, being in the age range of 20-49 years, obesity, regular alcohol consumption, and comorbidity, but not smoking status or pregnancy, were related to a high incidence of local or systemic adverse events after H1N1 vaccination. A total of 14 cases of adverse events were reported by the military doctors. In most reported cases, the subjects had fever in addition to the primary adverse event, and one patient was diagnosed with pneumonia. In conclusion, the overall burden of adverse events related to influenza A (H1N1) vaccination was not inconsequential, but most symptoms were mild. Female gender, middle-age range of 20-49 years, obesity, regular alcohol consumption, and comorbidity were risk factors for the occurrence of adverse events after H1N1 vaccination.

A decline in renal function is associated with loss of bone mass in Korean postmenopausal women with mild renal dysfunction.

This study was conducted to assess the relationship between estimated glomerular filtration rate (eGFR) and bone mineral density (BMD) in Korean postmenopausal women with mild renal dysfunction. A total of 328 postmenopausal women who underwent BMD measurement during health check-up was investigated. BMD was measured in lumbar spine (L1-L4), femoral neck, total proximal femur and femoral trochanteric areas by dual energy radiography absorptiometry and renal function was estimated by eGFR using Cockcroft-Gault equation. Of the 328 subjects, 317 (96.6%) had an eGFR ≥60 mL/min/1.73 m(2). By using simple linear regression analysis, age, height, weight and eGFR were significantly associated with BMD for the 4 aforementioned anatomic sites, while serum levels of creatinine and blood urea nitrogen did not influence BMD. When multiple regression analyses were applied, age and body weight still had significant associations with BMD at 4 different anatomic sites (P < 0.001). A significant association of eGFR with BMD remained in the lumbar spine, femoral neck and proximal total femur (P < 0.05) but not in the trochanteric area (P = 0.300). Our study suggests that a decline of renal function is associated with lower BMD in the lumbar spine, femoral neck and total proximal femur areas in Korean menopausal women with mild renal dysfunction.

Elevated peripheral blood monocyte fraction in nonalcoholic fatty liver disease.

An elevated white blood cell (WBC) count is associated with nonalcoholic fatty liver disease (NAFLD); however, a leukocyte subtype that is involved in the pathogenesis of NAFLD is not known. This study was conducted to investigate the association between NAFLD and WBC subtype fractions (%) among healthy elderly Koreans. A total of 794 subjects who underwent a health check-up were investigated. After excluding excessive alcohol intake and other liver diseases, NAFLD was diagnosed based on sonographic findings: hyperechogenecity of liver tissue, difference of echogenicity between liver and kidney, and visibility of vascular structures. The prevalence of NAFLD among entire cohort was 39.0% (310/794). The presence of NAFLD was significantly associated with higher blood WBC counts (5,485 ± 1073 vs. 5,230 ± 995 per mm(3), p = 0.001) and monocyte fraction (6.08 ± 2.40% vs. 5.12 ± 1.31%, p < 0.001). The multiple logistic regression analysis, after controlling confounders, including age, gender, body mass index, systolic and diastolic blood pressure, fasting blood glucose, alanine aminotransferase, triglyceride, and high-density lipoprotein cholesterol, showed that the prevalence risk of NAFLD was increased significantly according to the monocyte fraction quartiles: odds ratios (ORs) and 95% confidence intervals (CIs) for NAFLD were 1.00, 2.75 (1.63-4.62), 2.84 (1.67-4.84) and 5.17 (3.03-8.83), respectively. There were no significant associations between NAFLD and the total WBC count quartiles in this model. These results indicate that the elevated peripheral blood monocyte fraction is associated with NAFLD. The monocyte fraction might be a useful marker for NAFLD.

[Prognostic impact of Charlson comorbidity index obtained from medical records and claims data on 1-year mortality and length of stay in gastric cancer patients].

OBJECTIVES: We tried to evaluate the agreement of the Charlson comorbidity index values (CCI) obtained from different sources (medical records and National Health Insurance claims data) for gastric cancer patients. We also attempted to assess the prognostic value of these data for predicting 1-year mortality and length of the hospital stay (length of stay). METHODS: Medical records of 284 gastric cancer patients were reviewed, and their National Health Insurance claims data and death certificates were also investigated. To evaluate agreement, the kappa coefficient was tested. Multiple logistic regression analysis and multiple linear regression analysis were performed to evaluate and compare the prognostic power for predicting 1 year mortality and length of stay. RESULTS: The CCI values for each comorbid condition obtained from 2 different data sources appeared to poorly agree (kappa: 0.00-0.59). It was appeared that the CCI values based on both sources were not valid prognostic indicators of 1-year mortality. Only medical record-based CCI was a valid prognostic indicator of length of stay, even after adjustment of covariables (beta=0.112, 95% CI=[0.017-1.267]). CONCLUSIONS: There was a discrepancy between the data sources with regard to the value of CCI both for the prognostic power and its direction. Therefore, assuming that medical records are the gold standard for the source for CCI measurement, claims data is not an appropriate source for determining the CCI, at least for gastric cancer.

[Usefulness of comorbidity indices in operative gastric cancer cases].

OBJECTIVES: The purpose of the current study was to evaluate the usefulness of the following four comorbidity indices in gastric cancer patients who underwent surgery: Charlson Comorbidity Index (CCI), Cumulative Illness rating scale (CIRS), Index of Co-existent Disease (ICED), and Kaplan-Feinstein Scale (KFS). METHODS: The study subjects were 614 adults who underwent surgery for gastric cancer at K hospital between 2005 and 2007. We examined the test-retest and inter-rater reliability of 4 comorbidity indices for 50 patients. Reliability was evaluated with Spearman rho coefficients for CCI and CIRS, while Kappa values were used for the ICED and KFS indices. Logistic regression was used to determine how these comorbidity indices affected unplanned readmission and death. Multiple regression was used for determining if the comorbidity indices affected length of stay and hospital costs. RESULTS: The test-retest reliability of CCI and CIRS was substantial (Spearman rho=0.746 and 0.775, respectively), while for ICED and KFS was moderate (Kappa=0.476 and 0.504, respectively). The inter-rater reliability of the CCI, CIRS, and ICED was moderate (Spearman rho=0.580 and 0.668, and Kappa=0.433, respectively), but for KFS was fair (Kappa=0.383). According to the results from logistic regression, unplanned readmissions and deaths were not significantly different between the comorbidity index scores. But, according to the results from multiple linear regression, the CIRS group showed a significantly increased length of hospital stay (p<0.01). Additionally, CCI showed a significant association with increased hospital costs (p<0.01). CONCLUSIONS: This study suggests that the CCI index may be useful in the estimation of comorbidities associated with hospital costs, while the CIRS index may be useful where estimatation of comorbiditie associated with the length of hospital stay are concerned.

[The effect of the cost exemption policy for hospitalized children under 6 years old on the medical utilization in Korea].

OBJECTIVES: The Korean government in January 2006 instigated an exemption policy for hospitalized children under the age of six years old. This study examines how this policy affected the utilization of medical care in Korea. METHODS: A total of 1,513,797 claim records from the Health Insurance Review Agency were analyzed by complete enumeration methods. The changes of medical utilization were compared from 2005 to 2006. In addition, the changes of medical utilization between 2004 and 2005 were compared as a pseudo-control group. RESULTS: The admission rate increased 1.14-fold from 15.20% in 2004 to 17.32% in 2005, and this further increased 1.08-fold to 18.65% in 2006. The increase of patients with a common cold (1.2-fold) was higher than that of both the general patients (1.08-fold) and the patients with the top 10 fatal diseases (0.91-fold). The average length of stay per case for clinics showed the highest increase rates (1.06-fold). The rates of patients with the common cold showed a higher increase (1.05-fold) than that of the general patients. The average medical expense per case was increased by 1.10-fold from 2005 to 2006, which was higher than that from 2004 to 2005 (1.04-fold). The increase rate for patients with the common cold was higher at 1.18-fold than that of the general patients. CONCLUSIONS: The cost exemption policy has especially led to an increase in the utilization of clinics and the utilization by patients with a common cold.