Korea Seroprevalence Study of Monitoring of SARS-COV-2 Antibody Retention and Transmission (K-SEROSMART): findings from national representative sample.

OBJECTIVES: We estimated the population prevalence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including unreported infections, through a Korea Seroprevalence Study of Monitoring of SARS-CoV-2 Antibody Retention and Transmission (K-SEROSMART) in 258 communities throughout Korea. METHODS: In August 2022, a survey was conducted among 10,000 household members aged 5 years and older, in households selected through two stage probability random sampling. During face-to-face household interviews, participants self-reported their health status, COVID-19 diagnosis and vaccination history, and general characteristics. Subsequently, participants visited a community health center or medical clinic for blood sampling. Blood samples were analyzed for the presence of antibodies to spike proteins (anti-S) and antibodies to nucleocapsid proteins (anti-N) SARS-CoV-2 proteins using an electrochemiluminescence immunoassay. To estimate the population prevalence, the PROC SURVEYMEANS statistical procedure was employed, with weighting to reflect demographic data from July 2022. RESULTS: In total, 9,945 individuals from 5,041 households were surveyed across 258 communities, representing all basic local governments in Korea. The overall population-adjusted prevalence rates of anti-S and anti-N were 97.6% and 57.1%, respectively. Since the Korea Disease Control and Prevention Agency has reported a cumulative incidence of confirmed cases of 37.8% through July 31, 2022, the proportion of unreported infections among all COVID-19 infection was suggested to be 33.9%. CONCLUSIONS: The K-SEROSMART represents the first nationwide, community-based seroepidemiologic survey of COVID-19, confirming that most individuals possess antibodies to SARS-CoV-2 and that a significant number of unreported cases existed. Furthermore, this study lays the foundation for a surveillance system to continuously monitor transmission at the community level and the response to COVID-19.

Seroprevalence of SARS-CoV-2 antibodies during the third wave of COVID-19 in the Seoul metropolitan area of Korea.

OBJECTIVES: After the third wave of coronavirus disease 2019 (COVID-19), by mid-February 2021, approximately 0.16% of the Korean population was confirmed positive, which appeared to be among the lowest rates worldwide at that time. However, asymptomatic transmission is challenging for COVID-19 surveillance. Therefore, a community-based serosurvey of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was conducted to understand the effectiveness of Korea's strong containment strategy. METHODS: We collected 5,002 residual sera samples from January 30 to March 3, 2021, from 265 medical facilities in Seoul, 346 in Gyeonggi Province, and 57 in Incheon. Sixty samples from tertiary institutions were excluded. We defined the sub-regions according to the addresses of the medical facilities where the specimens were collected. Elecsys Anti-SARS-CoV-2 was used for screening, and positivity was confirmed using the SARS-CoV-2 sVNT Kit. Prevalence was estimated using sampling weights and the Wilson score interval for a binomial proportion with a 95% confidence interval. RESULTS: Among the 4,942 specimens, 32 and 25 tested positive for COVID-19 in the screening and confirmatory tests, respectively. The overall crude prevalence of SARS-CoV-2 antibodies was 0.51%. The population-adjusted overall prevalence was 0.55% in women and 0.38% in men. The region-specific estimation was 0.67% and 0.30% in Gyeonggi Province and Seoul, respectively. No positive cases were detected in Incheon. CONCLUSIONS: The proportion of undetected cases in Korea remained low as of early 2021. Therefore, an infection control strategy with exhaustive tracing and widespread pre-emptive testing appears to be effective in containing community spread of COVID-19.

Association among the exposure to giving knowledge, attitude and practice for handwashing in people residing in Seoul, South Korea: a retrospective cross-sectional study.

OBJECTIVES: Handwashing is known as the most preventive method for various infectious diseases. Health authorities have conducted various campaigns and public relations targeting the general population but few evaluations of these long-term interventions. This study aimed to investigate the association between experience of educational events or public relations (EXEP), attitude towards the effectiveness of handwashing (AEHW) and handwashing practice (HWP). SETTING: Using a population-based cross-sectional study with a complex sample design, we explored the response outcomes of handwashing. Those outcomes were collected biennially using Community Health Survey among the years 2013, 2015, 2017 and 2019. We applied multivariate logistic regression for the association among sociodemographic factors, health conditions, EXEP, AEHW and HWP. PARTICIPANTS: Total participants residing in Seoul were 23 139 (men 44.2%), 23 004 (men 44.4%), 22 955 (men 44.8%) and 22 930 (men 43.9%), in 2013, 2015, 2017 and 2019, respectively. RESULTS: Overall, participants with EXEP are more likely to be women, aged between the 30s and 60s, and with a higher educational level. Particularly, participants with EXEP had an increased association with HWP (OR 1.21, 95% CI 1.19 to 1.33) and AEHW (OR 1.50, 95% CI 1.38 to 1.63). In addition, AEHW also had an increased association with HWP (OR 1.67, 95% CI 1.53 to 1.81). The mediated effect of AEHW to HWP is not determined evidently. CONCLUSION: The results showed that EXEP is positively associated with HWP and AEHW among community-dwelling people. Our results confirm that educational activity can lead to more pronounced behavioural changes only when it forms a positive attitude.

Generic Logic Model for Coronavirus Disease-2019 Responses Based on the South Korean Experience.

BACKGROUND: As the global coronavirus disease-2019 (COVID-19) pandemic continues, many countries have implemented public health policies, such as lockdowns and physical distancing measures, to prevent its spread. South Korea's response to COVID-19, which prevented an increase in confirmed cases and increased resilience, has been considered very effective. PURPOSE: To analyze Korea's response to COVID-19 in 2020 and develop a logic model to evaluate performance effectiveness in follow-up studies. METHODS: By content analysis of Korea Disease Control and Prevention Agency (KDCA) press releases, we defined the problems and identified the causes of the health and social effects of the COVID-19 outbreak. Next, we created a problem tree and developed a logic model that comprised inputs, activities, outputs, outcomes, and impacts. Finally, we held expert consultations to obtain expert opinions regarding the logic model and to ensure the model's validity. RESULTS: South Korea's COVID-19 response policy mitigated the social and health impacts. The 2020 COVID-19 responses had four outcomes (identifying cases on time, preventing transmission of coronavirus infection, effective treatment of COVID-19 cases, protecting public resilience and well-being) and 12 outputs; South Korea conducted 32 activities. CONCLUSION: The results can be a practical reference for managing problems faced in other countries. Korean policy may be of interest in the future for international decision-makers in charge of policy enforcement and those who may be called on to respond to new infectious diseases.

Municipal Residence Level of Long-Term PM10 Exposure Associated with Obesity among Young Adults in Seoul, Korea.

BACKGROUND: long-term effects of ambient pollutants used to be defined in cohort studies using biomarkers. Health effects on young adults from long-term exposure to particulate matters (PM) in residential ambiance have received less attention. METHODS: using the data of population-representative aged 19-29 in Seoul, the relationship between obesity and PM10 levels of the living district was examined. We defined obesity as Body Mass Index (BMI) 25 kg/m2 and more. Survey logistic regression was conducted according to individual residence periods in the current municipality. Individual characteristics were adjusted overall and were age-specific; aged 19-24 and 25-29. RESULTS: study population was 3655 (1680 (46%) men and 1933 aged 19-24 (52.9%)) individuals. Relationship between length of residence in municipalities with a greater level of PM10 from 2001-2005 and obesity was increased over the residing period; 10 years ≤ (odds ratio (OR) 1.071, 95% confidence interval (CI) 0.969-1.185), 15 years ≤ (1.120, 1.006-1.247), and 20 years ≤ (1.158, 1.034-1.297) in aged 19-29. Age-specific effects showed slight differences. CONCLUSIONS: Although PM10 levels are currently decreasing, higher levels of PM10 exposure in the residential area during the earlier lifetime may contribute to obesity increase among young adults.

The association between wind-related variables and stroke symptom onset: A case-crossover study on Jeju Island.

BACKGROUND: Although several studies have investigated the effects of ambient temperature on the risk of stroke, few studies have examined the relationship between other meteorological conditions and stroke. Therefore, the aim of this study was to analyze the association between wind-related variables and stroke symptoms onset. METHODS: Data regarding the onset of stroke symptoms occurring between January 1, 2006, and December 31, 2007 on Jeju Island were collected from the Jeju National University Hospital stroke registry. A fixed-strata case-crossover analysis based on time of onset and adjusted for ambient temperature, relative humidity, air pressure, and pollutants was used to analyze the effects of wind speed, the daily wind speed range (DWR), and the wind chill index on stroke symptom onset using varied lag terms. Models examining the modification effects by age, sex, smoking status, season, and type of stroke were also analyzed. RESULTS: A total of 409 stroke events (381 ischemic and 28 hemorrhagic) were registered between 2006 and 2007. The odds ratios (ORs) for wind speed, DWR, and wind chill among the total sample at lag 0-8 were 1.18 (95% confidence interval (CI): 1.06-1.31), 1.08 (95% CI: 1.02-1.14), and 1.22 (95% CI: 1.07-1.39) respectively. The ORs for wind speed, DWR, and wind chill for ischemic stroke patients were slightly greater than for patients in the total sample (OR=1.20, 95% CI: 1.08-1.34; OR=1.09, 95% CI: 1.03-1.15; and OR=1.22, 95% CI: 1.07-1.39, respectively). Statistically significant season-specific effects were found for spring and winter, and various delayed effects were observed. In addition, age, sex, and smoking status modified the effect size of wind speed, DWR, and wind chill. CONCLUSIONS: Our analyses showed that the risk of stroke symptoms onset was associated with wind speed, DWR, and wind chill on Jeju Island.

Effect change of obesity on diabetes depending on measurement: self-reported body mass index from 2012 Community Health Survey vs. directly measured from the Korea National Health and Nutrition Examination Survey.

OBJECTIVES: Obesity is a well-recognized risk factor for type 2 diabetes mellitus (DM) among young and middle-aged adults in South Korea. To elaborate on the association between obesity and Diabetes mellitus (DM), subjective data from self-reporting survey or objective data from health examination is generally used. This study was conducted to validate the change of association from using these different measurements. METHODS: Community Health Survey data and Korea National Health and Nutrition Examination Survey data, as subjective and objective data respectively, were used. Population, resident in Seoul and over 45 aged, were selected for the study and the association between obesity and DM were defined by using multivariate logistic regression model. RESULTS: In subjective data, DM prevalence was 12.4% (male, 14.7; female, 10.6) and obesity prevalence was 26.0% (male, 29.2; female, 23.4). Whereas, in objective data, DM prevalence was 15.0% (male, 17.8; female, 12.9), and obese population was 32.4% (male, 34.4; female, 30.8). Based on the effect of obesity on DM prevalence from each data, using objective data increased the impact of obesity. Difference of relative risk of obesity between from subjective data and from objective was bigger in female than male and statistically significant. CONCLUSIONS: The differences of association pattern between subjective and objective data were found, due to higher obesity prevalence in objective data, and discrepancies of socio-economic status. These discrepancies could be inevitable Therefore we have to face them proactively, and understand the different aspect of various variables from different measurement.

Clarithromycin-based standard triple therapy can still be effective for Helicobacter pylori eradication in some parts of the Korea.

We evaluated the antibiotic resistance rates and eradication rates of clarithromycin based triple therapy from 2005 to 2010 retrospectively. In addition, we investigated the mechanism of clarithromycin resistance in Helicobacter pylori strains isolated from Korean patients. Two hundred and twelve strains of H. pylori were isolated from 204 patients. H. pylori ATCC 43504 was used as the standard strain. The eradication rates of H. pylori from 2005 to 2010 were 89.3%, 82.6%, 86.3%, 87.7%, 81.8%, and 84.2%, respectively. Total eradication rate was 84.9%. DNA sequences of the 23S RNA gene in clarithromycin-resistant strains were determined. The resistance rates of H. pylori to amoxicillin, clarithromycin, metronidazole, tetracycline, ciprofloxacin, moxifloxacin, and levofloxacin were 9.0%, 8.5%, 36.3%, 0%, 14.2%, 14.2%, and 14.2%, respectively. The multidrug resistance rate of H. pylori was 16.5%. Sequence analysis of clarithromycin-resistant strains showed an A2144G mutation in 8 of 14 strains (57.1%), a T2183C mutation in 5 of 14 strains (35.7%), and double mutations of both A2144G and T2183C in 1 of 14 strains (7.1%). In the present study, triple therapy may still be an effective eradication therapy for H. pylori infections in Korea. The A2144G and T2183C mutations are mainly present in clarithromycin-resistant isolates.

Self-reported anthropometric information cannot vouch for the accurate assessment of obesity prevalence in populations of middle-aged and older Korean individuals.

While there are strong correlations between self-reported and directly measured anthropometric data, the discrepancy and systematic errors associated with these, particularly among middle-aged and older persons residing in South Korea, remain a contentious issue. All participants were selected from the Korean Longitudinal Study of Aging (KLoSA), a panel study conducted by the Korea Labor Institute; data from 510 participants (290 females; 56.9%) were analyzed. We considered general characteristics, including sex, age, education, marital status, employment, income, and residential region, and used self-rated health (SRH) as a generic indicator of health status. One-way ANOVA, t-test, and Scheffé's test (α=0.1) were employed to explore the difference between directly measured and self-reported values. Sensitivity and specificity values were used to assess the validity of obesity diagnoses based on self-reported body mass index (BMI: body weight in kilograms divided by the square of height in meters). The means of BMI differences were 1.3 (±1.2)kg/m(2) among men and 1.8 (±1.5)kg/m(2) among women. In men, the difference could be attributed to measured BMI and residential region; among women, age and education level influenced the discrepancy in BMI. Scheffé's test (α=0.1) for multiple comparisons of group means revealed that women over the age of 65 years, with lower than middle-school education, who lived in rural areas, and had a measured BMI of 25kg/m(2) or more, were more likely to have significant BMI discrepancies. In contrast, for men, significant predictors were living in rural areas and being obese. Although adequate correlations were seen in self-reported BMI, they indicated low sensitivity, with 46.5% and 60.1% among males and females, respectively. However, specificities were very high, at 97.8% and 98.0% for males and females, respectively. The diagnostic performance of self-reported BMI is insufficient for assessing obesity prevalence among middle-aged or older Koreans.