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.

Association between levels of exposure to heavy metals and renal function indicators of residents in environmentally vulnerable areas.

Abandoned metal mines and refineries are considered environmentally vulnerable areas owing to high levels of exposure to heavy metals. This study examined the association between heavy metal exposure and renal function indicators. We studied a total of 298 participants, of which 74 and 68 resided in low- and high-exposure abandoned metal mine areas, respectively, with 121 in the refinery area and 35 in the control area. Blood and urine samples were collected from the participants to analyze the levels of blood lead, cadmium, and creatinine and urinary cadmium, NAG, and ß2-MG. The estimated glomerular filtration rate, which is calculated using the Chronic Kidney Disease Epidemiology Collaboration equation, was used for assessments. The study participants comprised more females than males, and their mean age was 70.3 years. The blood lead and cadmium as well as urinary cadmium levels were 2.12 µg/dL, 1.89 µg/L, and 2.11 µg/L, respectively, in the heavy metal-exposure areas, and 1.18 µg/dL, 0.89 µg/L, and 1.11 µg/L, respectively, in the control area. The odds ratio (OR) for exceeding the reference value showed that blood cadmium in the refinery area was 38 times higher than that in the control area. Urinary cadmium was seven times higher in the low-exposure abandoned metal mine area than in the control area. NAG showed a positive correlation with urinary cadmium in all areas. In the refinery area, correlations were observed between ß2-MG and urinary cadmium levels and the eGFR and blood cadmium level; in the high-exposure abandoned metal mine area, correlations were observed between NAG, ß2-MG, and the eGFR and blood cadmium. In this study, the association between Cd exposure and some renal function indicators was observed. This study's findings and the obtained biological samples can serve as a basis for future molecular biological research.

The relationship between the fish consumption and blood total/methyl-mercury concentration of costal area in Korea.

The purpose of this study was to evaluate the relationship between fish consumption and blood THg/MeHg concentration in Korean adults by measuring MeHg concentration in blood directly. The study subjects consisted of 400 adults aged 20 or older from 30 subareas in Busan, Ulsan and Gyeongsangnam-do province in Korea from August to October, 2010. We tried to recruit the same number of male and female participants in different age groups (20s, 30s, 40s, 50s and 60s) and allocated 13-16 subjects by district to represent Hg concentration in the research areas. The geometric means of THg and MeHg concentration in blood were 5.27 µg/L (5.00-5.57) and 4.05 µg/L (3.81-4.32), respectively. The proportion of MeHg/THg concentration was 78.53% (77.09-79.97). MeHg concentration was higher in coastal areas (4.26 µg/L) than in inland areas (3.52 µg/L) and was higher in men (4.68 µg/L) than in women (3.52 µg/L). In male participants, blood MeHg concentration increased with increasing annual fish consumption, and the proportion of MeHg/THg concentration showed an upward trend as THg concentration increased. However, none of the measures of the proportion of MeHg/THg showed significant differences. This is the first report in Korea about the relationship between blood MeHg concentration and related factors. Our findings suggest that MeHg concentration is affected by fish consumption as well as by gender difference and drinking status. Since the pathological mechanism has not been clarified, additional studies are needed for explaining the biological and lifestyle differences in the risk of adverse health effects by Hg exposure.