COVID-19 in South Korea.

A novel coronavirus (severe acute respiratory syndrome-CoV-2) that initially originated from Wuhan, China, in December 2019 has already caused a pandemic. While this novel coronavirus disease (COVID-19) frequently induces mild diseases, it has also generated severe diseases among certain populations, including older-aged individuals with underlying diseases, such as cardiovascular disease and diabetes. As of 31 March 2020, a total of 9786 confirmed cases with COVID-19 have been reported in South Korea. South Korea has the highest diagnostic rate for COVID-19, which has been the major contributor in overcoming this outbreak. We are trying to reduce the reproduction number of COVID-19 to less than one and eventually succeed in controlling this outbreak using methods such as contact tracing, quarantine, testing, isolation, social distancing and school closure. This report aimed to describe the current situation of COVID-19 in South Korea and our response to this outbreak.

National Trends in Sadness, Suicidality, and COVID-19 Pandemic-Related Risk Factors Among South Korean Adolescents From 2005 to 2021.

Importance: Despite the COVID-19 pandemic's effect on daily life, limited research exists on the prevalence and risk factors of suicidality and sadness among South Korean adolescents. Objectives: To examine whether the observed sadness and suicidality in the early to middle periods of the COVID-19 pandemic differed from the expected level and to investigate changes in risk factors for sadness and suicidality. Design, Setting, and Participants: This nationwide serial cross-sectional survey study used data on 1 109 776 Korean adolescents aged 13 to 18 years from the Korea Youth Risk Behavior Web-based Survey from 2005 to 2021. Exposure: The COVID-19 pandemic. Main Outcomes and Measures: The pattern of changes in the percentage or proportion of sadness or suicidality, as well as the risk factors for sadness or suicidality. The transitional effect of the COVID-19 pandemic was assessed using weighted odds ratios (wORs) or weighted beta coefficients with 95% CIs. Results: Between 2005 and 2021, 1 109 776 adolescents (mean [SD] age, 15.0 [1.7] years; 51.5% male adolescents; and 51.7% in grades 7-9 and 48.3% in grades 10-12) were included in the Korea Youth Risk Behavior Web-based Survey. The slope of the long-term trends in sadness and suicidality decreased in the prepandemic period (sadness: from 37.8% [95% CI, 37.4%-38.2%] in 2005-2007 to 26.1% [95% CI, 25.9%-26.4%] in 2016-2019; suicidality: from 23.0% [95% CI, 22.7%-23.3%] in 2005-2007 to 12.3% [95% CI, 12.1%-12.5%] in 2016-2019), whereas the slope increased during the COVID-19 pandemic (sadness: from 25.0% [95% CI, 24.5%-25.6%] in 2020 to 26.6% [95% CI, 26.1%-27.1%] in 2021; trend difference in ß, 0.249 [95% CI, 0.236-0.262]; suicidality: from 10.7% [95% CI, 10.3%-11.1%] in 2020 to 12.5% [95% CI, 12.1%-12.9%] in 2021; trend difference in ß, 0.328 [95% CI, 0.312-0.344]). The trends presented a similar tendency in the subgroups according to sex, school grade, residential area, smoking status, and current alcohol use. Compared with the prepandemic period, the risk factors associated with sadness during the pandemic were younger age (wOR, 0.907; 95% CI, 0.881-0.933), female sex (wOR, 1.031; 95% CI, 1.001-1.062), urban residence (wOR, 1.120; 95% CI, 1.087-1.153), current smoking status (wOR, 1.134; 95% CI, 1.059-1.216), and current alcohol use (wOR, 1.051; 95% CI, 1.002-1.102). Female sex (wOR, 1.064; 95% CI, 1.021-1.109), urban residence (wOR, 1.117; 95% CI, 1.074-1.162), and low economic status (wOR, 1.286; 95% CI, 1.180-1.403) were the risk factors significantly associated with suicidality after the COVID-19 pandemic began. Conclusions and Relevance: In this nationwide serial cross-sectional survey study of South Korean adolescents, the slope of the prevalence of sadness and suicidality increased during the COVID-19 pandemic after a decrease prior to the pandemic. The findings suggest that public health measures are needed to recognize vulnerable groups with risk factors and to prevent an increase in sadness and suicidality among adolescents during the COVID-19 pandemic.

Physical distancing and emergency medical services utilization after self-harm in Korea during the early COVID-19 pandemic: A nationwide quantitative study.

BACKGROUND: People experienced various stress and psychological responses to the coronavirus disease 2019 (COVID-19) pandemic. This study aimed to examine the changes in emergency medical services (EMSs) utilization by self-harm patients in early pandemic and the impacts of physical distancing measures on the EMSs utilization by self-harm patients. METHODS: Data for all patients presenting to emergency departments (EDs) after self-harm injuries including self-poisoning were collected from the National ED Information System (NEDIS). Characteristics of patients in two study regions (urban versus rural) were compared. Weekly and annual ED visit rates after self-harm (VRSH) per 100,000 population were calculated. Mobile phone mobility index (MPMI) was calculated by dividing a region's aggregated mobile phone mobility by mid-year population. Joinpoint regression analysis was conducted to assess changes in 2020 over pre-pandemic years. Test for presence of joinpoint at the end of 2019 was performed. A cross-correlation function was used to estimate the maximal morphological similarity and lag time between changes in MPMI and VRSH. RESULTS: In 2020, in early phases of the pandemic, there was a moderate decline in self-harm-related ED visits to 30,797 from a continuously increasing trend seen in previous years. However, proportions of young people (50.1%) and females (62.3%) increased over previous years. VRSHs among women and young people aged 15-34 years showed higher levels in 2020 than in previous five years. There was a significant decrease in the proportion of patients transported directly from the scene. In addition, there was a polarization of mental state upon ED arrival from alert and unresponsive. The median correlation coefficient between MPMI values and VRSH values was 0.601 (interquartile range [IQR]: 0.539-0.619) in urban regions and 0.531 (IQR: 0.454-0.595) in rural regions, showing no statistically significant difference between the two. CONCLUSION: Physical distancing measures adopted to prevent the spread of transmittable diseases following the pandemic had the effect of decreasing ED visits due to self-harm. When the pandemic has ended, and daily life has been restored, it will be particularly important to pay attention to the increased numbers of self-harm patients expected to visit EDs compared to during the pandemic.

The association between depression and non-compliance with COVID-19 preventive behaviors in South Korean older adults stratified by sex.

OBJECTIVES: This study evaluated the association between depression and non-compliance with COVID-19 preventive behaviors among community-dwelling South Korean older adults. METHODS: We utilized the 2020 Korean Community Health Survey-a community-based nationwide survey. A score of 10 points or higher on the Patient Health Questionnaire-9 was defined as depression. Non-compliance with COVID-19 preventive behaviors was assessed on the following three behaviors: washing hands, wearing masks, and watching distance. We also included socio-demographic characteristics, health behaviors, and COVID-19-related characteristics as covariates. Multiple logistic regression analyses were performed, and all statistical analyses were stratified by sex. RESULTS: The 70,693 participants included 29,736 men and 40,957 women. Notably, 2.3% of men and 4.2% of women had depression. Non-compliance with washing hands was significantly higher in men than women (1.3% vs. 0.9%), whereas no significant differences were observed in wearing masks and watching distance. The adjusted logistic regression analysis showed that depression was positively associated with non-compliance with washing hands and watching distance in both sexes. The association between depression and non-compliance with wearing masks was significant only in women. CONCLUSIONS: There was an association between depression and non-compliance with COVID-19 preventive behaviors in South Korean older adults. This signifies that health providers need to reduce depression to improve compliance with preventive behaviors in older adults.

Association between COVID-19 lockdown and sleep behaviors in Korean adolescents.

To find the effect of coronavirus disease 2019 (COVID-19)-related sleep behavior changes using school-based self-reported data from a nationally representative Korean adolescent population. We analyzed web-based self-reported data from the Korean Youth Risk Behavior Web-based Survey in 98,126 participants (51,651 in 2019 [before the COVID-19 pandemic]; 46,475 in 2020 [during COVID-19 pandemic] 12 through 18 years old were included in this study. Self-report questionnaires were used to assess socioeconomic status, health behaviors, psychological factors, and sleep patterns. During the COVID-19 pandemic, Korean adolescents had a later weekend bedtime (≥1:00 am: 68.2% vs 71.5%, P < .001) and late weekend wake time (≤7:00 am: 13.3% vs 10.7%, P < .001) compared to before COVID-19 pandemic. Average sleep duration (434.7 ± 102.6 vs 428.2 ± 100.4 minutes; P < .001) was significantly lower during the COVID-19 pandemic and weekend catch-up sleep >2 hours (42.1% vs 43.7%; P < .001), late chronotype (17.1% vs 22.9%, P < .001) were significantly higher during COVID-19 pandemic. After adjusting for multiple confounding variables, short sleep duration (≦5 hours, odds ratio [OR] 1.14; 95% confidence interval [CI] 1.10-1.19), 6 hours, OR 1.07; 95% CI 1.03-1.12), long weekend catch-up sleep (OR, 1.08; 95% CI, 1.06-1.11) and late chronotype (OR, 1.43; 95% CI, 1.38-1.47) were significantly associated with COVID-19 pandemic. The COVID-19 pandemic was associated with changes in sleep behavior among Korean adolescents, resulting in later bed and wake-up times, increased weekend catch-up sleep, and a shift of chronotype toward eveningness.

Trends in the Quality of Primary Care and Acute Care in Korea From 2008 to 2020: A Cross-sectional Study.

OBJECTIVES: Measuring the quality of care is paramount to inform policies for healthcare services. Nevertheless, little is known about the quality of primary care and acute care provided in Korea. This study investigated trends in the quality of primary care and acute care. METHODS: Case-fatality rates and avoidable hospitalization rates were used as performance indicators to assess the quality of primary care and acute care. Admission data for the period 2008 to 2020 were extracted from the National Health Insurance Claims Database. Case-fatality rates and avoidable hospitalization rates were standardized by age and sex to adjust for patients' characteristics over time, and significant changes in the rates were identified by joinpoint regression. RESULTS: The average annual percent change in age-/sex-standardized case-fatality rates for acute myocardial infarction was -2.3% (95% confidence interval, -4.6 to 0.0). For hemorrhagic and ischemic stroke, the age-/sex-standardized case-fatality rates were 21.8% and 5.9%, respectively in 2020; these rates decreased since 2008 (27.1 and 8.7%, respectively). The average annual percent change in age-/sex-standardized avoidable hospitalization rates ranged from -9.4% to -3.0%, with statistically significant changes between 2008 and 2020. In 2020, the avoidable hospitalization rates decreased considerably compared with the 2019 rate because of the coronavirus disease 2019 pandemic. CONCLUSIONS: The avoidable hospitalization rates and case-fatality rates decreased overall during the past decade, but they were relatively high compared with other countries. Strengthening primary care is an essential requirement to improve patient health outcomes in the rapidly aging Korean population.

COVID-19 vaccination-related myocarditis: a Korean nationwide study.

AIMS: A comprehensive nationwide study on the incidence and outcomes of COVID-19 vaccination-related myocarditis (VRM) is in need. METHODS AND RESULTS: Among 44 276 704 individuals with at least 1 dose of COVID-19 vaccination, the incidence and clinical courses of VRM cases confirmed by the Expert Adjudication Committee of the Korea Disease Control and Prevention Agency were analyzed. COVID-19 VRM was confirmed in 480 cases (1.08 cases per 100 000 persons). Vaccination-related myocarditis incidence was significantly higher in men than in women (1.35 vs. 0.82 per 100 000 persons, P < 0.001) and in mRNA vaccines than in other vaccines (1.46 vs. 0.14 per 100 000 persons, P < 0.001). Vaccination-related myocarditis incidence was highest in males between the ages of 12 and 17 years (5.29 cases per 100 000 persons) and lowest in females over 70 years (0.16 cases per 100 000 persons). Severe VRM was identified in 95 cases (19.8% of total VRM, 0.22 per 100 000 vaccinated persons), 85 intensive care unit admission (17.7%), 36 fulminant myocarditis (7.5%), 21 extracorporeal membrane oxygenation therapy (4.4%), 21 deaths (4.4%), and 1 heart transplantation (0.2%). Eight out of 21 deaths were sudden cardiac death (SCD) attributable to VRM proved by an autopsy, and all cases of SCD attributable to VRM were aged under 45 years and received mRNA vaccines. CONCLUSION: Although COVID-19 VRM was rare and showed relatively favorable clinical courses, severe VRM was found in 19.8% of all VRM cases. Moreover, SCD should be closely monitored as a potentially fatal complication of COVID-19 vaccination.

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.

Association between Consumption of Dietary Supplements and Chronic Kidney Disease Prevalence: Results of the Korean Nationwide Population-Based Survey.

Despite the enormous global market of dietary supplements, the impact of dietary supplements on kidney disease is still unclear. Based on the National Health and Nutrition Examination Survey from 2015 to 2017, this study evaluated the association between dietary supplement and chronic kidney disease (CKD) in 13,271 Korean adults. Among the dietary supplements, vitamin and mineral intake was the highest at 61.41%, followed by omega-3 fatty acids at 11.85%, and ginseng at 7.99%. The prevalence of CKD was significantly higher in those who consumed amino acids and proteins, ginseng and red ginseng, and herbal medicine (plant extract)-berries than in those who did not. Conversely, patients who consumed probiotic supplements had a significantly lower prevalence of CKD than those who did not. In the population without CKD risk factors or history of CKD, the prevalence of CKD was high in the group consuming ginseng and red ginseng. After adjusting for covariates, the herbal medicine (plant extract)-berry group showed an independent association with CKD incidence. In conclusion, it is suggested that dietary supplements may affect kidney function. Further large-scale cohort studies are required to elucidate the exact effects of each dietary supplement on CKD.

The association mental health of adolescents with economic impact during the COVID-19 pandemic: a 2020 Korean nationally representative survey.

BACKGROUND: COVID-19 has affected innumerable aspects of life, including education, economy, and religion. Economic problems and inequality are associated with poor mental health in adolescents. This study aimed to identify the relationship between economic damage to families due to COVID-19 and various mental health problems in Korean adolescents and to evaluate the risk factors of mental health. METHODS: In total, 54,948 Korean adolescent students from 398 middle and 395 high schools were surveyed between August and November 2020. Complex sample logistic regression was performed to calculate odds ratios (ORs) and 95% confidence intervals (CI) for depression and suicidal ideation, respectively. A generalized linear model analysis was used to examine the association between mental health (unhappiness, loneliness, and stress) and the economic impact of COVID-19. Analyses were adjusted for age, gender, school grade, perceived academic achievement, perceived family economic status, and economic support. RESULTS: The ORs of depression (OR = 1.77, 95% CI:1.57-2.00), suicidal ideation (OR = 2.14, 95% CI:1.84-2.50), unhappiness (OR = 1.51 95% CI 1.42-1.60) and lonely (OR = 1.38 95% CI 1.27-1.49) for the low level of perceived family economic status was higher compared to middle level. Adolescents who experienced economic deterioration in their households as COVID-19 showed a higher risk of depression (OR = 1.42, 95% CI:1.35-1.49), suicide ideation (OR = 1.36, 95% CI:1.28-1.44), unhappiness (OR = 2.23 95% CI 2.19-2.27), lonely (OR = 1.20 95% CI 1.17-1.22), and stress (OR = 1.14 95% CI 1.12-1.16) than those who did not. CONCLUSIONS: The findings revealed an association between the decline in household economic status due to COVID-19 and mental health problems, such as stress, loneliness, suicidal ideation, depression, and unhappiness.

Changes in food and nutrient intakes in Korean adults before and during the COVID-19 pandemic: data from the 2011-2020 Korea National Health and Nutrition Examination Survey.

OBJECTIVES: This study was to examine the changes in dietary habits and food and nutrient intakes between before (2019) and during (2020) the coronavirus disease 2019 (COVID-19) pandemic from the Korea National Health and Nutrition Examination Survey (KNHANES). METHODS: A total of 54,995 participants aged ≥19 years who participated in the 2011-2020 KNHANES were included. The 10-year trend (2011-2020) and differences between 2019 and 2020 for dietary habits and food and nutrient intakes were estimated using SAS. RESULTS: In the past 10 years (2011-2020), the dietary habits (increase in skipping meals and eating out), food intake (increase in meats and decrease in fruits and vegetables), and nutrient intake (increase in fat and decrease in sodium) in adults have changed. When comparing between 2019 and 2020, there were 4.6%p decrease in the eating out more than once a day. On the other hand, there were no significant differences in the intakes of food, energy and most of nutrients between 2019 and 2020, except for the proportion of energy intake from fat (1.0%p increase) and carbohydrate (1.0%p decrease). CONCLUSIONS: Although a change in dietary habits from before to during the COVID-19 pandemic was observed, food and nutrient intakes have not deteriorated markedly and appear similar to the trends in the past 10 years. Throughout the COVID-19 pandemic, it is necessary to monitor the effects of changes in dietary habits on health as well as food and nutrient intakes.

Trends in health behaviors and mental health among Korean adolescents in Korea over 5 years, 2017-2021: focusing on the comparisons before and during the COVID-19 pandemic.

Objectives: We investigated recent trends in health behaviors and mental health conditions among Korean adolescents from 2017 to 2021 and compared the changes before and during the coronavirus disease 2019 (COVID-19) pandemic. Methods: Data analysis was conducted on 289,415 adolescents participating in the Korea Youth Risk Behavior Web-Based Survey, an annual cross-sectional study from 2017 to 2021. All analysis was conducted using sex stratification, and the annual percentage change (APC) was calculated. Results: Alcohol consumption and smoking decreased in the first year of the COVID-19 pandemic compared with before, except for girls from the low-income level. The prevalence of inadequate physical activity for both boys and girls increased in 2020 compared with the pre-COVID-19 period and decreased again by 2021. The prevalence of obesity in both sexes increased regardless of the period (boys, APC = 8.2%, 95% confidence intervals (CI), 6.4-10.1; girls, APC = 3.3%, 95% CI, 1.8-4.8). The prevalence of stress, depression, and suicidal ideation, plans, and attempts for both sexes decreased in 2020 compared to the pre-COVID-19 period. By 2021, this prevalence had returned to a level similar to before the pandemic. No significant APC changes were observed in the prevalence of mental health. Conclusions: These findings demonstrate the trends and APCs in health behaviors and mental health conditions among Korean adolescents over the last 5 years. We must pay attention to the heterogeneous and multifaceted features of the COVID-19 pandemic.

Self-reported adverse events after 2 doses of COVID-19 vaccine in Korea.

OBJECTIVES: In Korea, a national coronavirus disease 2019 (COVID-19) vaccination program was implemented, including 4 vaccines against COVID-19. A text messaging-based survey, in addition to a passive adverse event reporting system, was launched to quickly report unusual symptoms post-vaccination. This study compared the frequency of adverse events after COVID-19 vaccination based on the vaccine type and the type of 2-dose regimen (homologous or heterologous). METHODS: Self-reported adverse events were collected through a text-message survey for 7 days after each vaccination. This study included 50,950 vaccine recipients who responded to the survey at least once. Informed consent to receive surveys via text was obtained from the vaccine recipients on the date of first vaccination. RESULTS: The recipients of mRNA vaccines reported local and systemic reactions 1.6 times to 2.8 times more frequently after dose 2 than after dose 1 (p<0.001), whereas ChAdOx1-S recipients reported significantly fewer local and systemic reactions after dose 2 than after dose 1 (p<0.001). Local and systemic reactions were approximately 2 times and 4 times more frequent for heterologous vaccination than for BNT162b2/BNT162b2 and ChAdOx1-S/ChAdOx1-S regimens, respectively. Young individuals, female, and those receiving heterologous vaccine regimens including ChAdOx1-S/BNT162b2 vaccines reported more adverse events than older participants, male, and those with homologous vaccine regimens. CONCLUSIONS: Although a heterologous regimen, youth, and female sex were associated with a higher risk of adverse reactions after COVID-19 vaccination, no critical issues were noted. Active consideration of heterologous schedules based on the evidence of efficacy and safety appears desirable.

Analysis of the Effects of COVID-19 on Hip Fractures in Korea Without Lockdown: Interrupted Time Series Analysis Using a Nationwide Cohort.

BACKGROUND: The purpose of this study was to investigate the change in the incidence rate, length of hospital stay (LOS), in-hospital mortality rate, and surgical method of hip fractures during the coronavirus disease 2019 (COVID-19) pandemic in South Korea where lockdown restrictions were not implemented. METHODS: We calculated the expected values of the incidence of hip fractures, in-hospital mortality and LOS of hip fracture patients in 2020 (COVID period) based hip fracture database of the Korean National Health Insurance Review and Assessment (HIRA) during a 9-year period from 2011 to 2019 (pre-COVID period). A generalized estimating equation model with Poisson distribution and logarithmic link function was used to estimate adjusted annual percent change (PC) of incidence rate and 95% confidence intervals (CIs). Then, we compared the annual incidence, in-hospital mortality rate and LOS in 2020 with the expected values. RESULTS: The overall incidence rate of hip fracture in 2020 was not significantly different from the expected value (PC, -5%; 95% CI, -13 to 4; P = 0.280). In women, the incidence rate of hip fracture in age groups over 70 years was smaller than the predicted value (P < 0.001). The in-hospital mortality rate was not significantly different from the expected value (PC, 5%; 95% CI, -8 to 19; P = 0.461). The mean LOS was larger than the expected value by 2% (PC, 2%; 95% CI, 1 to 3; P < 0.001). In intertrochanteric fracture, the proportion of internal fixation was smaller than the predicted value by 2% (PC, -2%; 95% CI, -3 to -1; P < 0.001), and that of hemiarthroplasty was larger than the predicted value by 8% (PC, 8%; 95% CI, 4 to 14; P < 0.001). CONCLUSIONS: In 2020, the incidence rate of hip fracture did not significantly decrease, and in-hospital mortality rate did not significantly increase compared to the expected rates, which were projected based on the HIRA hip fracture data from 2011 to 2019. Only LOS increased slightly.

The impact of COVID-19 on screening for colorectal, gastric, breast, and cervical cancer in Korea.

OBJECTIVES: The coronavirus disease 2019 (COVID-19) pandemic has affected the utilization of healthcare services, including participation in cancer screening programs. We compared cancer screening participation rates for colorectal, gastric, breast, and cervical cancers among participants in the National Cancer Screening Program (NCSP) in 2019 and 2020 to address the potential distraction effect of COVID-19 on cancer screening. METHODS: Data from the NCSP for 4 cancer types (stomach, colorectal, breast, and cervical) in 2019 and 2020 were used to calculate cancer screening participation rates by calendar month, gender, age group, and geographical region. Monthly participation rates were analyzed per 1,000 eligible individuals. RESULTS: The screening participation rate decreased in 2020 compared to 2019 for all 4 cancers: colorectal (40.5 vs. 35.3%), gastric (61.9 vs. 54.6%), breast (63.8 vs. 55.8%), and cervical (57.8 vs. 52.2%) cancers. Following 2 major COVID-19 waves in March and December 2020, the participation rates in the 4 types of cancer screening dropped compared with those in 2019. The highest decline was observed in the elderly population aged 80 years and older (percentage change: -21% for colorectal cancer; -20% for gastric cancer; -26% for breast cancer; -20% for cervical cancer). CONCLUSIONS: After the 2 major COVID-19 waves, the screening participation rate for 4 types of cancer declined compared with 2019. Further studies are needed to identify the indirect effects of the COVID-19 pandemic on cancer patients, such as delayed diagnoses of cancer or excess cancer deaths.

Widespread Household Transmission of SARS-CoV-2 B.1.1.529 (Omicron) Variant from Children, South Korea, 2022.

The role that children play in the transmission of the omicron variant is unclear. Here we report an outbreak that started in young children attending various pediatric facilities, leading to extensive household transmission that affected 75 families with 88 confirmed case-patients in 3 weeks. Tailored social and public health measures directed towards children and pediatric facilities are warranted with the emergence of highly transmissible omicron variant to mitigate the impact of coronavirus diseases 2019 (COVID-19).

Malnutrition as a major related factor of frailty among older adults residing in long-term care facilities in Korea.

OBJECTIVES: The objectives of this study were 1) to investigate the prevalence and co-existence of frailty and malnutrition and 2) to identify factors related to frailty (including malnutrition) according to the level of frailty. METHODS: Data collection was conducted from July 11, 2021, to January 23, 2022, in 558 older adults residing in 16 long-term care facilities (LTCFs) in Korea. The FRAIL-NH and Mini-Nutritional Assessment short form were used to measure frailty and nutrition, respectively. The data analysis included descriptive statistics and a multivariate logistic regression. RESULTS: The mean age of the participants was 83.68 (± 7.39) years. Among 558 participants, 37 (6.6%), 274 (49.1%), and 247 (44.3%) were robust, prefrail, and frail, respectively. At the same time, 75.8% were categorized as having malnutrition status (malnourished: 18.1%; risk of malnutrition: 57.7%), and 40.9% had co-existing malnutrition and frailty. In the multivariate analysis, malnutrition was identified as the major frailty-related factor. Compared with a normal nutritional status, the incidence of frailty in the malnutrition group was 10.35 times (95% CI: 3.78-28.36) higher than the incidence of robustness and 4.80 times (95% CI: 2.69-8.59) higher than the incidence of prefrail. CONCLUSION: The prevalence of frailty and malnutrition, and their co-existence, among older adults residing in LTCFs was high. Malnutrition is a major factor that increases the incidence of frailty. Therefore, active interventions are needed to improve the nutritional status of this population.

Association of Physical Activity With SARS-CoV-2 Infection and Severe Clinical Outcomes Among Patients in South Korea.

Importance: The association of moderate to vigorous physical activity (MVPA) with COVID-19 outcomes is unclear and needs to be investigated. Objective: To identify the association of longitudinal changes in MVPA with SARS-CoV-2 infection and severe COVID-19 outcomes. Design, Setting, and Participants: This nested case-control study used data from 6 396 500 adult patients in South Korean who participated in National Health Insurance Service (NHIS) biennial health screenings from period 1 (2017-2018) to period 2 (2019-2020). Patients were followed from October 8, 2020, until the diagnosis of COVID-19 or December 31, 2021. Exposure: Moderate to vigorous physical activity was measured by self-report on questionnaires during both NHIS health screenings and calculated by adding the frequency (times per week) of each moderate (≥30 minutes per day) and vigorous (≥20 minutes per day) physical activity. Main Outcomes and Measures: The main outcomes were a positive diagnosis of SARS-CoV-2 infection and severe COVID-19 clinical events. Adjusted odds ratio (aORs) and 99% CIs were calculated using multivariable logistic regression analysis. Results: A total of 183 350 patients with COVID-19 (mean [SD] age, 51.9 [13.8] years; female, 89 369 [48.7%]; male, 93 981 [51.3%]) among 2 110 268 participants were identified. For participants with vs without COVID-19, the proportion of MVPA frequency at period 2 was 35.8% vs 35.9% for physically inactive, 18.9% vs 18.9% for 1 to 2 times per week, 17.7% vs 17.7% for 3 to 4 times per week, and 27.5% vs 27.4% for 5 or more times per week. Among unvaccinated, physically inactive patients at period 1, the odds for infection increased when engaged in MVPA 1 to 2 times per week (aOR, 1.08; 99% CI, 1.01-1.15), 3 to 4 times per week (aOR, 1.09; 99% CI, 1.03-1.16), or 5 or more times per week (aOR, 1.10; 99% CI, 1.04-1.17) at period 2. Conversely, among unvaccinated patients with MVPA of 5 or more times per week at period 1, the odds for infection decreased when engaged 1 to 2 times per week (aOR, 0.90; 99% CI, 0.81-0.98) or physically inactive (aOR, 0.80; 99% CI, 0.73-0.87) at period 2. The trend of MVPA and incident infection was mitigated when participants were fully vaccinated. Furthermore, the odds for severe COVID-19 showed significant but limited associations with MVPA. Conclusions and Relevance: The findings of this nested case-control study show a direct association of MVPA with risk of SARS-CoV-2 infection, which was mitigated after completion of the COVID-19 vaccination primary series. In addition, higher levels of MVPA were associated with a lower risk of severe COVID-19 outcomes to limited proportions.

Trends in Depressive Symptoms and Suicidality of South Korean Adolescents: Comparison of Expected and Observed Prevalence During the COVID-19 Pandemic.

PURPOSE: Depressive symptoms and suicidality of adolescents during the COVID-19 pandemic are emerging public health issues. However, there is a lack of representative studies on adolescents' mental health that considers the preceding secular trends. METHODS: This descriptive study used nationally representative cross-sectional data of Korean adolescents from the Korea Youth Risk Behavior Survey from 2005 to 2020 (N = 1,035,382). We utilized joinpoint regression analysis to explore the temporal prevalence trends of depressive symptoms, suicidal ideation, and suicide attempts. Based on the annual percentage change until 2019, the expected and actual prevalence in 2020 (N = 54,948) was compared to describe departures of prevalence from the trend line. These trends between sex, school level, ethnic status, and socioeconomic status were also compared. RESULTS: Considering the recent increase in secular trends until 2019, the actual observed values in 2020 were lower than expected by 13% in depressive symptoms, 20% in suicidal ideation, and 40% in suicide attempts. The gap between sexes, school levels, ethnic status, and socioeconomic groups was similar or narrowed in 2020 compared to previous trends. DISCUSSION: We observed a lower prevalence of depressive symptoms and suicidality among Korean adolescents than expected about 9 months from the beginning of the COVID-19 pandemic despite the recent increase in secular trends.