National trends in alcohol and substance use among adolescents from 2005 to 2021: a Korean serial cross-sectional study of one million adolescents.

BACKGROUND: Although previous studies have provided data on early pandemic periods of alcohol and substance use in adolescents, more adequate studies are needed to predict the trends of alcohol and substance use during recent periods, including the mid-pandemic period. This study investigated the changes in alcohol and substance use, except tobacco use, throughout the pre-, early-, and mid-pandemic periods in adolescents using a nationwide serial cross-sectional survey from South Korea. METHODS: Data on 1,109,776 Korean adolescents aged 13-18 years from 2005 to 2021 were obtained in a survey operated by the Korea Disease Control and Prevention Agency. We evaluated adolescents' alcohol and substance consumption prevalence and compared the slope of alcohol and substance prevalence before and during the COVID-19 pandemic to see the trend changes. We define the pre-COVID-19 period as consisting of four groups of consecutive years (2005-2008, 2009-2012, 2013-2015, and 2016-2019). The COVID-19 pandemic period is composed of 2020 (early-pandemic era) and 2021 (mid-pandemic era). RESULTS: More than a million adolescents successfully met the inclusion criteria. The weighted prevalence of current alcohol use was 26.8% [95% confidence interval (CI) 26.4-27.1] from 2005 to 2008 and 10.5% (95% CI 10.1-11.0) in 2020 and 2021. The weighted prevalence of substance use was 1.1% (95% CI 1.1-1.2) from 2005 to 2008 and 0.7% (95% CI 0.6-0.7) between 2020 and 2021. From 2005 to 2021, the overall trend of use of both alcohol and drugs was found to decrease, but the decline has slowed since COVID-19 epidemic (current alcohol use: ßdiff 0.167; 95% CI 0.150-0.184; substance use: ßdiff 0.152; 95% CI 0.110-0.194). The changes in the slope of current alcohol and substance use showed a consistent slowdown with regard to sex, grade, residence area, and smoking status from 2005 to 2021. CONCLUSION: The overall prevalence of alcohol consumption and substance use among over one million Korean adolescents from the early and mid-stage (2020-2021) of the COVID-19 pandemic showed a slower decline than expected given the increase during the prepandemic period (2005-2019).

Changes in Otorhinolaryngologic Disease Incidences before and during the COVID-19 Pandemic in Korea.

This study aimed to investigate the change in the incidence and variance of otorhinolaryngologic diseases during the coronavirus disease 19 (COVID-19) pandemic. The entire Korean population (~50 million) was evaluated for the monthly incidence of 11 common otorhinolaryngologic diseases of upper respiratory infection (URI), influenza, acute tonsillitis, peritonsillar abscess, retropharyngeal and parapharyngeal abscess, acute laryngitis and bronchitis, stomatitis and related lesions, acute sinusitis, rhinitis, otitis media, and dizziness from January 2018 through March 2021 using the International Classification of Disease (ICD)-10 codes with the data of the Korea National Health Insurance Service. The differences in the mean incidence of 11 common otorhinolaryngologic diseases before and during COVID-19 were compared using the Mann-Whitney U test. The differences in the variance of incidence before and during COVID-19 were compared using Levene's test. The incidence of all 11 otorhinolaryngologic diseases was lower during COVID-19 than before COVID-19 (all p < 0.05). The variations in disease incidence by season were lower during COVID-19 than before COVID-19 for infectious diseases, including URI, influenza, acute tonsillitis, peritonsillar abscess, retropharyngeal and parapharyngeal abscess, acute laryngitis and bronchitis, acute sinusitis, and otitis media (all p < 0.05), while it was not in noninfectious diseases, including stomatitis, rhinitis, and dizziness. As expected, the incidences of all otorhinolalryngolgic diseases were decreased. Additionally, we found that seasonal variations in infectious diseases disappeared during the COVID-19 pandemic, while noninfectious diseases did not.

Estimated prevalence and trends in smoking among adolescents in South Korea, 2005-2021: a nationwide serial study.

BACKGROUND: Although smoking is classified as a risk factor for severe COVID-19 outcomes, there is a scarcity of studies on prevalence of smoking during the COVID-19 pandemic. Thus, this study aims to analyze the trends of prevalence of smoking in adolescents over the COVID-19 pandemic period. METHODS: The present study used data from middle to high school adolescents between 2005 and 2021 who participated in the Korea Youth Risk Behavior Web-based Survey (KYRBS). We evaluated the smoking prevalence (ever or daily) by year groups and estimated the slope in smoking prevalence before and during the pandemic. RESULTS: A total of 1,137,823 adolescents participated in the study [mean age, 15.04 years [95% confidence interval (CI) 15.03-15.06]; and male, 52.4% (95% CI 51.7-53.1)]. The prevalence of ever smokers was 27.7% (95% CI 27.3-28.1) between 2005 and 2008 but decreased to 9.8% (95% CI 9.3-10.3) in 2021. A consistent trend was found in daily smokers, as the estimates decreased from 5.4% (95% CI 5.2-5.6) between 2005 and 2008 to 2.3% (95% CI 2.1-2.5) in 2021. However, the downward slope in the overall prevalence of ever smokers and daily smokers became less pronounced in the COVID-19 pandemic period than in the pre-pandemic period. In the subgroup with substance use, the decreasing slope in daily smokers was significantly more pronounced during the pandemic than during the pre-pandemic period. CONCLUSIONS: The proportion of ever smokers and daily smokers showed a less pronounced decreasing trend during the pandemic. The findings of our study provide an overall understanding of the pandemic's impact on smoking prevalence in adolescents. Supplementary file2 (MP4 64897 KB).

National trends in physical activity among adolescents in South Korea before and during the COVID-19 pandemic, 2009-2021.

With the ongoing COVID-19 pandemic, several previous studies from different countries showed that physical activity (PA) decreased during the COVID-19 outbreak. However, few studies have examined the recent tendency of PA in the adolescent population. Thus, we aimed to investigate the long-term trend of PA in Korean youth and the prevalence changes between before and during the COVID-19 pandemic. Data from Korea Youth Risk Behavior Web-Based Survey (KYRBS) was collected for consecutive years between 2009 and 2021. The period was separated into prepandemic (2009-2019), early-pandemic (2020), and mid-pandemic (2021). Self-reported amount of PA was categorized into four groups (insufficient, aerobic, muscle strengthening, and both physical activities) according to World Health Organization (WHO) PA guidelines. A total of 840 488 adolescents aged 12-18 who fully responded to the survey were selected (response rate: 95.2%). The 13-year trends in the proportion of adolescents who reported aerobic and muscle-strengthening activities met or exceeded 2020 WHO exercise guidelines for adolescents plateaued (11.9% from 2009 to 2011, 14.2% from 2018 to 2019, 14.4% from 2020, and 14.0% from 2021); however, the slope decreased during the pandemic (ßdiff , -0.076; 95% confidence interval [CI], -0.123 to -0.029). Proportion of sufficient aerobic exercise among adolescents sharply decreased midst the pandemic (28.0% from 2009 to 2011, 29.4% from 2018 to 2019, and 23.8% from 2020; ßdiff , -0.266; 95% CI, -0.306 to -0.226) but increased again in 2021 (26.0% from mid-COVID 19; 95% CI, 25.4-26.7). Similar patterns were observed in Metabolic Equivalent Task (MET) score (MET-min/week; 804.1 from 2018 to 2019, 720.9 from 2020, and 779.6 from 2021). The mean difference in MET score between pre-COVID and post-COVID was -55.4 MET-min/week (95% CI, -70.5 to -40.3). Through a nationwide representative study, there was no significant difference with regard to the number of Korean adolescents who achieved the PA guidelines (pre and postpandemic); however, the prevalence of recommended levels of PA needs to increase more based on the trend before the COVID-19 outbreak. The findings of this study suggest reinforcement of the importance of public health policies for Korean youths to be more physically active, especially during and after the pandemic.

Statin Use and COVID-19 Infectivity and Severity in South Korea: Two Population-Based Nationwide Cohort Studies.

BACKGROUND: Basic studies suggest that statins as add-on therapy may benefit patients with COVID-19; however, real-world evidence of such a beneficial association is lacking. OBJECTIVE: We investigated differences in SARS-CoV-2 test positivity and clinical outcomes of COVID-19 (composite endpoint: admission to intensive care unit, invasive ventilation, or death) between statin users and nonusers. METHODS: Two independent population-based cohorts were analyzed, and we investigated the differences in SARS-CoV-2 test positivity and severe clinical outcomes of COVID-19, such as admission to the intensive care unit, invasive ventilation, or death, between statin users and nonusers. One group comprised an unmatched cohort of 214,207 patients who underwent SARS-CoV-2 testing from the Global Research Collaboration Project (GRCP)-COVID cohort, and the other group comprised an unmatched cohort of 74,866 patients who underwent SARS-CoV-2 testing from the National Health Insurance Service (NHIS)-COVID cohort. RESULTS: The GRCP-COVID cohort with propensity score matching had 29,701 statin users and 29,701 matched nonusers. The SARS-CoV-2 test positivity rate was not associated with statin use (statin users, 2.82% [837/29,701]; nonusers, 2.65% [787/29,701]; adjusted relative risk [aRR] 0.97; 95% CI 0.88-1.07). Among patients with confirmed COVID-19 in the GRCP-COVID cohort, 804 were statin users and 1573 were matched nonusers. Statin users were associated with a decreased likelihood of severe clinical outcomes (statin users, 3.98% [32/804]; nonusers, 5.40% [85/1573]; aRR 0.62; 95% CI 0.41-0.91) and length of hospital stay (statin users, 23.8 days; nonusers, 26.3 days; adjusted mean difference -2.87; 95% CI -5.68 to -0.93) than nonusers. The results of the NHIS-COVID cohort were similar to the primary results of the GRCP-COVID cohort. CONCLUSIONS: Our findings indicate that prior statin use is related to a decreased risk of worsening clinical outcomes of COVID-19 and length of hospital stay but not to that of SARS-CoV-2 infection.

Changes in mean and variance of ophthalmic disease incidences during COVID-19 pandemic in Korea.

This study undertook to determine the changes in the numbers of outpatient visits for various ophthalmic diseases during the COVID-19 pandemic compared with before. The monthly outpatient visits for 14 common ophthalmic diseases were enumerated based on the ICD-10 codes in Korean National Health Insurance Service data. The differences in the mean outpatient visits and disease variance 'before' and 'during COVID-19' were calculated. Subsequently, subgroup analyses according to age and sex were performed. The number of outpatient visits for conjunctivitis, scleritis & episcleritis, keratitis, cataract, diabetic retinopathy, and traumatic ophthalmic disease were lower during than before COVID-19 (all P < 0.001). The lower numbers of outpatient visits for ophthalmic disorders during COVID-19 were consistent across the age and sex subgroups. All ophthalmic diseases other than endophthalmitis showed no change of variation 'during' relative to 'before' COVID-19. In conclusion, during the COVID-19 pandemic, the ophthalmic outpatient visits decreased for infectious and inflammatory diseases, screening diseases, and traumatic diseases. However, COVID-19 is not considered to have had a significant effect on variation.

Incidence of Asthma, Atopic Dermatitis, and Allergic Rhinitis in Korean Adults before and during the COVID-19 Pandemic Using Data from the Korea National Health and Nutrition Examination Survey.

The prevalence of allergic diseases has been increasing globally prior to COVID-19. The pandemic resulted in changes in lifestyle and personal habits such as universal mask-wearing and social distancing. However, there is insufficient information on the impact of the COVID-19 pandemic on the prevalence of allergic conditions such as asthma, atopic dermatitis, and allergic rhinitis. We analyzed the incidence rate for self-reported and doctor-diagnosed cases of allergic diseases of asthma, atopic dermatitis, and allergic rhinitis. A total of 15,469 subjects were registered from a national cohort dataset of the National Health and Nutrition Examination Survey. Using multiple logistic regression analysis, we calculated the adjusted odds ratio (OR) for each disease in 2020 compared to 2019. Subgroup analyses were performed according to age and sex. There were no statistically significant differences between the incidence of doctor-diagnosed and current allergic diseases in 2019 and 2020 (asthma, p = 0.667 and p = 0.268; atopic dermatitis, p = 0.268 and p = 0.973; allergic rhinitis, p = 0.691 and p = 0.942, respectively), and subgroup analysis showed consistent results. Among the Korean population from 2019 to 2020, the incidence of the allergic diseases asthma, atopic dermatitis, and allergic rhinitis did not decrease as expected.

Development of an IoT-integrated multiplexed digital PCR system for quantitative detection of infectious diseases.

For rapid detection of the COVID-19 infection, the digital polymerase chain reaction (dPCR) with higher sensitivity and specificity has been presented as a promising method of point-of-care testing (POCT). Unlike the conventional real-time PCR (qPCR), the dPCR system allows absolute quantification of the target DNA without a calibration curve. Although a number of dPCR systems have previously been reported, most of these previous assays lack multiplexing capabilities. As different variants of COVID-19 have rapidly emerged, there is an urgent need for highly specific multiplexed detection systems. Additionally, the advances in the Internet of Things (IoT) technology have enabled the onsite detection of infectious diseases. Here, we present an IoT-integrated multiplexed dPCR (IM-dPCR) system involving sample compartmentalization, DNA amplification, fluorescence imaging, and quantitative analysis. This IM-dPCR system comprises three modules: a plasmonic heating-based thermal cycler, a multi-color fluorescence imaging set-up, and a firmware control module. Combined with a custom-developed smartphone application built on an IoT platform, the IM-dPCR system enabled automatic processing, data collection, and cloud storage. Using a self-priming microfluidic chip, 9 RNA groups (e.g., H1N1, H3N2, IFZ B, DENV2, DENV3, DENV4, OC43, 229E, and NL63) associated with three infectious diseases (e.g., influenza, dengue, and human coronaviruses) were analyzed with higher linearity (>98%) and sensitivity (1 copy per µL). The IM-dPCR system exhibited comparable analytical accuracy to commercial qPCR platforms. Therefore, this IM-dPCR system plays a crucial role in the onsite detection of infectious diseases.

Depression, Stress, and Suicide in Korean Adults before and during the COVID-19 Pandemic Using Data from the Korea National Health and Nutritional Examination Survey.

This study investigated changes in the prevalence of depression, stress, and suicidal attempts during the COVID-19 pandemic. The ≥19-year-old population in the Korea National Health and Nutrition Examination Survey in 2019 and 2020 was included. The histories of depression, stress, and suicidal attempts were compared between the 2019 and 2020 cohorts using multiple logistic regression analysis with complex sampling. The prevalence of depression was not significantly different between the 2019 and 2020 groups (4.1% vs. 4.5%, p = 0.326). The prevalence of stress and suicide attempts was also not significantly different between groups (all p > 0.05). The rates of depression, stress, and suicide attempts were not associated with the 2020 group compared to the 2019 group (all p > 0.05). The 19- to 39-year-old group in the 2020 group indicated a higher rate of depression (diagnosed by physicians) than the 19- to 39-year-old group in the 2019 group (adjusted odds ratio = 1.58, 95% confidence intervals = 1.00-2.50, p = 0.049). The risks of depression, stress, and suicidal attempts were not related to the COVID-19 pandemic in Korean adults. A young adult population demonstrated an increased risk of depression associated with the COVID-19 pandemic.

Physical Activity and Sedentary Time in Korean Adults before and during the COVID-19 Pandemic Using Data from the Korea National Health and Nutritional Examination Survey.

Several recent studies suggested reduced physical activity (PA) related to the COVID-19 pandemic without consensus. This study investigated the changes in PA and sedentary time during the COVID-19 pandemic compared to before the COVID-19 era. The Korea National Health and Nutrition Examination Survey 2019 and 2020 were used. The ≥19-year-old population was examined in 2019 and 2020 for time spent engaging in high- and moderate-intensity PA and sedentary time. Based on the recommended level of PA by the World Health Organization, ≥75 min/wk of high PA and ≥150 min/of moderate PA were classified. A sedentary time of ≥120 min/d was selected. Multiple logistic regression analysis with complex sampling was conducted for ≥75 min/wk of high PA, ≥150 min/wk of moderate PA, and ≥120 min/d of sedentary time in the 2020 group compared to the 2019 group. The ≥75 min/wk high PA was not lower in the 2020 group than in the 2019 group (adjusted odds ratio (aOR) = 0.96, 95% confidence intervals (95% CIs) = 0.79-1.18, P = 0.696). The ≥150 min/wk of moderate PA was also not lower in the 2020 group (aOR = 1.12, 95% CI = 0.94-1.32, p = 0.201). However, the ≥150 min/wk of moderate PA in the female group was higher in the 2020 group than in the 2019 group (aOR = 1.29, 95% CI = 1.01-1.65, p = 0.042). Sedentary time ≥ 120 min/d was lower in the 2020 group (aOR = 0.35, 95% CI = 0.17-0.72, p = 0.005). This association was consistent in the 19-39-year-old and female group. In conclusion, during the COVID-19 pandemic, high and moderate PA were not decreased in Korean adults, while sedentary time was reduced.

Investigation of changes in the physical activity and fall experience before and after the COVID-19 pandemic.

This study aimed to investigate the changes in physical activity levels and the rate of falls during the COVID-19 pandemic in the Korean population. The Korean Community Health Survey (KCHS) conducted in 2019 was compared with that conducted in 2020. Simple or multiple linear regression with complex sampling was conducted to calculate the estimated value (EV) of physical activity in the 2020 group vs. the 2019 group. The odds ratio (OR) of fall histories was calculated using simple or multiple logistic regression with complex sampling for the 2020 group compared to the 2019 group. The time spent on vigorous and moderate physical activity was lower in the 2020 group than in the 2019 group (EV = -10.0, 95% CI = -12.1 to -8.0, P < 0.001 for vigorous exercise and EV = -24.0, 95% CI = -26.7 to -21.4, P < 0.001 for moderate exercise). The rate of falls was lower in the 2020 group than in the 2019 group (OR = 0.66, 95% CI = 0.62 to 0.70, P < 0.001). Vigorous and moderate exercise decreased after the COVID-19 pandemic compared to before the pandemic. The occurrence of falls was lower during the COVID-19 pandemic than in the pre-pandemic period.

In vivo imaging of invasive aspergillosis with 18F-fluorodeoxysorbitol positron emission tomography.

Invasive aspergillosis is a critical complication in immunocompromised patients with hematologic malignancies or with viral pneumonia caused by influenza virus or SARS­CoV­2. Although early and accurate diagnosis of invasive aspergillosis can maximize clinical outcomes, current diagnostic methods are time-consuming and poorly sensitive. Here, we assess the ability of 2-deoxy-2-18F-fluorosorbitol (18F-FDS) positron emission tomography (PET) to specifically and noninvasively detect Aspergillus infections. We show that 18F-FDS PET can be used to visualize Aspergillus fumigatus infection of the lungs, brain, and muscles in mouse models. In particular, 18F-FDS can distinguish pulmonary aspergillosis from Staphylococcus aureus infection, both of which induce pulmonary infiltrates in immunocompromised patients. Thus, our results indicate that the combination of 18F-FDS PET and appropriate clinical information may be useful in the differential diagnosis and localization of invasive aspergillosis.

Changes in the Mean of Medical Visits Due to Psychiatric Disease in Korean Children and Adolescents before and during the COVID-19 Pandemic.

The COVID-19 pandemic has been suggested to have adverse impacts on psychiatric disorders. This study aimed to investigate the changes in medical visits due to a wide range of psychiatric disorders in children during the COVID-19 pandemic. The medical visits of all Korean children and adolescents (0-19 years old) due to the 12 following psychiatric disorders were investigated: autism; attention-deficit/hyperactivity disorder (ADHD); depressive disorder; bipolar disorder; primary insomnia; schizophrenia; panic disorder; hypochondriasis; posttraumatic stress disorder (PTSD); anxiety disorder; anorexia nervosa; and adephagia. The mean medical visits before and during the COVID-19 pandemic were compared. The mean number of clinical visits due to autism, ADHD, depressive disorder, bipolar disorder, panic disorder, hypochondriasis, PTSD, anxiety disorder, and anorexia nervosa was higher during the COVID-19 pandemic than before the COVID-19 pandemic (all p < 0.05). The higher mean number of medical visits due to psychiatric disorders was maintained in age and sex subgroups. The female and adolescent groups demonstrated a higher mean number of medical visits due to psychiatric disorders during the COVID-19 pandemic. The medical visits due to many psychiatric disorders were higher during the COVID-19 pandemic than before COVID-19 in children and adolescents in Korea. Women and adolescents were more susceptible to psychiatric disorders during the COVID-19 pandemic.

Changes in the Mean of and Variance in Psychological Disease Incidences before and during the COVID-19 Pandemic in the Korean Adult Population.

The coronavirus disease 2019 (COVID-19) pandemic has been suggested to increase the risk of depression and anxiety disorders. This study expanded upon previous findings by estimating the changes in medical visits for various psychological disorders during the COVID-19 pandemic compared to before COVID-19. The entire Korean population ≥ 20 years old (~42.3 million) was included. The first COVID-19 case in Korea was reported on 20 January 2020. Thus, the period from January 2018 through to February 2020 was classified as "before COVID-19", and the period from March 2020 through to May 2021 was classified as "during COVID-19". Monthly medical visits due to the following 13 psychological disorders were evaluated: depressive disorder, bipolar disorder, primary insomnia, schizophrenia, panic disorder, hypochondriasis, posttraumatic stress disorder (PTSD), anxiety disorder, anorexia nervosa, addephagia, alcoholism, nicotine dependency, and gambling addiction were evaluated. The differences in the number of medical visits and the variance of diseases before and during the COVID-19 pandemic were analyzed using the Mann-Whitney U test and Levene's test. Subgroup analyses were conducted according to age and sex. The frequencies of medical visits for depressive disorder, bipolar disorder, primary insomnia, panic disorder, hypochondriasis, PTSD, anxiety disorder, anorexia nervosa, addephagia, and gambling addiction were higher during COVID-19 than before COVID-19 (all p < 0.001). However, the frequencies of medical visits for schizophrenia, alcoholism, and nicotine dependency were lower during the COVID-19 pandemic than before the COVID-19 pandemic (all p < 0.001). The psychological disorders with a higher frequency of medical visits during COVID-19 were consistent in all age and sex subgroups. In the old age group, the number of medical visits due to schizophrenia was also higher during COVID-19 than before COVID-19 (p < 0.001). Many psychological disorders, including depressive disorder, bipolar disorder, primary insomnia, panic disorder, hypochondriasis, PTSD, anxiety disorder, anorexia nervosa, addephagia, and gambling addiction, had a higher number of related medical visits, while disorders such as schizophrenia, alcoholism, and nicotine dependency had a lower number of related medical visits during COVID-19 among Korean adults.

Assessment of the difference in depressive symptoms of the Korean adult population before and during the COVID-19 pandemic using a community health survey.

BACKGROUND: The aim of this study was to evaluate the rate of depression during the COVID-19 pandemic compared to that during the prepandemic period. METHODS: Data from participants in the Korean Community Health Survey in 2019 and 2020 aged ≥ 19 years old were analyzed. In total, the data of 223,306 participants from the 2020 group were compared with the data of 217,133 participants from the 2019 group regarding the experience and severity of depression. The experience of depression was surveyed in terms of a history of sadness or despair for ≥2 weeks in the last year. In addition, the PHQ-9 scores were used, and participants with PHQ-9 scores ≥10 were recategorized as having moderate to severe depression. The odds for depression of the 2020 group compared to the 2019 group based on the survey and PHQ-9 scores were calculated using simple or multiple logistic regression with complex sampling with weighted values. RESULTS: The rate of depression experience was lower in the 2020 group than in the 2019 group. The odds of experiencing depression were lower in the 2020 group than in the 2019 group (adjusted odds ratio [aOR] = 0.95, 95% confidence intervals [95% CI] = 0.91-0.98, P = 0.004). The odds of moderate to severe depression were also lower in the 2020 group than in the 2019 group (aOR=0.92, 95% CI=0.88-0.97, P = 0.001). CONCLUSION: The rate of depression experience was not higher during the COVID-19 pandemic than during the prepandemic period in Korea.

Comparison of Stress and Suicide-Related Behaviors Among Korean Youths Before and During the COVID-19 Pandemic.

Importance: The COVID-19 pandemic has had a substantial psychological effect on young people. A quantitative assessment of the association between the pandemic and stress and suicidality in youths is needed. Objective: To investigate the association of the COVID-19 pandemic with self-reported stress and suicide-related behaviors in youths. Design, Setting, and Participants: This cross-sectional study used data from the the Korea Youth Risk Behavior Web-based Survey (KYRBWS) conducted in 2019 and 2020 with youths aged 12 to 18 years. Statistical analysis was performed from January to February 2021. Main Outcomes and Measures: The odds ratios (ORs) with 95% CIs for subjective stress level, sadness or despair, suicidal thoughts, suicide planning, and suicide attempts among 2020 participants were compared with those of the 2019 participants using multiple logistic regression analysis with complex sampling using weighted values. Results: The 48 443 youths in the 2019 KYRBWS (24 917 male youths [51.3%]; mean [SD] age, 15.0 [1.7] years) and the 44 216 youths in the 2020 KYRBWS (23 103 male youths [52.5%]; mean [SD] age, 15.1 [1.7] years) were compared. The degree of subjective stress was lower in the 2020 participants than in the 2019 participants (severe stress: adjusted OR [aOR], 0.90 [95% CI, 0.83-0.97]; very severe stress: aOR, 0.65 [95% CI, 0.60-0.72]). Sadness or despair was also lower in the 2020 participants than in the 2019 participants (aOR, 0.81 [95% CI, 0.78-0.84]). There were fewer suicide-related behaviors, including suicidal thoughts, suicide planning, and suicide attempts, among the 2020 participants than among the 2019 participants (suicidal thoughts: aOR, 0.77 [95% CI, 0.73-0.80]; suicide planning: aOR = 0.88 [95% CI, 0.81-0.96]; suicide attempts: aOR, 0.64 [95% CI, 0.58-0.70]). Conclusions and Relevance: This cross-sectional study found that severe stress, sadness or despair and suicide-related behaviors had inverse associations with the early COVID-19 pandemic in Korean youths. These findings suggest that levels of high stress decreased among Korean youths in the early period of the pandemic compared with prepandemic levels.

The associations of previous influenza/upper respiratory infection with COVID-19 susceptibility/morbidity/mortality: a nationwide cohort study in South Korea.

We aimed to investigate the associations of previous influenza/URI with the susceptibility of COVID-19 patients compared to that of non-COVID-19 participants. A nationwide COVID-19 cohort database was collected by the Korea National Health Insurance Corporation. A total of 8,070 COVID-19 patients (1 January 2020 through 4 June 2020) were matched with 32,280 control participants. Severe COVID-19 morbidity was defined based on the treatment histories of the intensive care unit, invasive ventilation, and extracorporeal membrane oxygenation and death. The susceptibility/morbidity/mortality associated with prior histories of 1-14, 1-30, 1-90, 15-45, 15-90, and 31-90 days before COVID-19 onset were analyzed using conditional/unconditional logistic regression. Prior influenza infection was related to increased susceptibility to COVID-19 (adjusted odds ratio [95% confidence interval] = 3.07 [1.61-5.85] for 1-14 days and 1.91 [1.54-2.37] for 1-90 days). Prior URI was also associated with increased susceptibility to COVID-19 (6.95 [6.38-7.58] for 1-14 days, 4.99 [4.64-5.37] for 1-30 days, and 2.70 [2.55-2.86] for 1-90 days). COVID-19 morbidity was positively associated with influenza (3.64 [1.55-9.21] and 3.59 [1.42-9.05]) and URI (1.40 [1.11-1.78] and 1.28 [1.02-1.61]) at 1-14 days and 1-30 days, respectively. Overall, previous influenza/URI did not show an association with COVID-19 mortality. Previous influenza/URI histories were associated with increased COVID-19 susceptibility and morbidity. Our findings indicate why controlling influenza/URI is important during the COVID-19 pandemic.

Autoimmune inflammatory rheumatic diseases and COVID-19 outcomes in South Korea: a nationwide cohort study.

BACKGROUND: Real-world evidence on the association between autoimmune inflammatory rheumatic diseases, therapies related to these diseases, and COVID-19 outcomes are inconsistent. We aimed to investigate the potential association between autoimmune inflammatory rheumatic diseases and COVID-19 early in the COVID-19 pandemic. METHODS: We did an exposure-driven, propensity score-matched study using a South Korean nationwide cohort linked to general health examination records. We analysed all South Korean patients aged older than 20 years who underwent SARS-CoV-2 RT-PCR testing between Jan 1 and May 30, 2020, and received general health examination results from the Korean National Health Insurance Service. We defined autoimmune inflammatory rheumatic diseases (inflammatory arthritis and connective tissue diseases) based on the relevant ICD-10 codes, with at least two claims (outpatient or inpatient) within 1 year. The outcomes were positive SARS-CoV-2 RT-PCR test, severe COVID-19 (requirement of oxygen therapy, intensive care unit admission, application of invasive ventilation, or death), and COVID-19-related death. Adjusted odds ratios (ORs) with 95% CIs were estimated after adjusting for the potential confounders. FINDINGS: Between Jan 1 and May 30, 2020, 133 609 patients (70 050 [52·4%] female and 63 559 [47·6%] male) completed the general health examination and were tested for SARS-CoV-2; 4365 (3·3%) were positive for SARS-CoV-2, and 8297 (6·2%) were diagnosed with autoimmune inflammatory rheumatic diseases. After matching, patients with an autoimmune inflammatory rheumatic disease showed an increased likelihood of testing positive for SARS-CoV-2 (adjusted OR 1·19, 95% CI 1·03-1·40; p=0·026), severe COVID-19 outcomes (1·26, 1·02-1·59; p=0·041), and COVID-19-related death (1·69, 1·01-2·84; p=0·046). Similar results were observed in patients with connective tissue disease and inflammatory arthritis. Treatment with any dose of systemic corticosteroids or disease-modifying antirheumatic drugs (DMARDs) were not associated with COVID-19-related outcomes, but those receiving high dose (≥10 mg per day) of systemic corticosteroids had an increased likelihood of a positive SARS-CoV-2 test (adjusted OR 1·47, 95% CI 1·05-2·03; p=0·022), severe COVID-19 outcomes (1·76, 1·06-2·96; p=0·031), and COVID-19-related death (3·34, 1·23-8·90; p=0·017). INTERPRETATION: Early in the COVID-19 pandemic, autoimmune inflammatory rheumatic diseases were associated with an increased likelihood of a positive SARS-CoV-2 PCR test, worse clinical outcomes of COVID-19, and COVID-19-related deaths in South Korea. A high dose of systemic corticosteroid, but not DMARDs, showed an adverse effect on SARS-CoV-2 infection and COVID-19-related clinical outcomes. FUNDING: National Research Foundation of Korea.