Background: The World Health Organization has declared the end of the coronavirus disease 2019 (COVID-19) public health emergency. However, this did not indicate the end of COVID-19. Several months after the infection, numerous patients complain of respiratory or nonspecific symptoms; this condition is called long COVID. Even patients with mild COVID-19 can experience long COVID, thus the burden of long COVID remains considerable. Therefore, we conducted this study to comprehensively analyze the effects of long COVID using multi-faceted assessments. Materials and Methods: We conducted a prospective cohort study involving patients diagnosed with COVID-19 between February 2020 and September 2021 in six tertiary hospitals in Korea. Patients were followed up at 1, 3, 6, 12, 18, and 24 months after discharge. Long COVID was defined as the persistence of three or more COVID-19-related symptoms. The primary outcome of this study was the prevalence of long COVID after the period of COVID-19. Results: During the study period, 290 patients were enrolled. Among them, 54.5 and 34.6% experienced long COVID within 6 months and after more than 18 months, respectively. Several patients showed abnormal results when tested for post-traumatic stress disorder (17.4%) and anxiety (31.9%) after 18 months. In patients who underwent follow-up chest computed tomography 18 months after COVID-19, abnormal findings remained at 51.9%. Males (odds ratio [OR], 0.17; 95% confidence interval [CI], 0.05–0.53; P=0.004) and elderly (OR, 1.04; 95% CI, 1.00–1.09; P=0.04) showed a significant association with long COVID after 12–18 months in a multivariable logistic regression analysis. Conclusion Many patients still showed long COVID after 18 months post SARS-CoV-2 infection. When managing these patients, the assessment of multiple aspects is necessary.

Background: The World Health Organization has declared the end of the coronavirus disease 2019 (COVID-19) public health emergency. However, this did not indicate the end of COVID-19. Several months after the infection, numerous patients complain of respiratory or nonspecific symptoms; this condition is called long COVID. Even patients with mild COVID-19 can experience long COVID, thus the burden of long COVID remains considerable. Therefore, we conducted this study to comprehensively analyze the effects of long COVID using multi-faceted assessments. Materials and Methods: We conducted a prospective cohort study involving patients diagnosed with COVID-19 between February 2020 and September 2021 in six tertiary hospitals in Korea. Patients were followed up at 1, 3, 6, 12, 18, and 24 months after discharge. Long COVID was defined as the persistence of three or more COVID-19-related symptoms. The primary outcome of this study was the prevalence of long COVID after the period of COVID-19. Results: During the study period, 290 patients were enrolled. Among them, 54.5 and 34.6% experienced long COVID within 6 months and after more than 18 months, respectively. Several patients showed abnormal results when tested for post-traumatic stress disorder (17.4%) and anxiety (31.9%) after 18 months. In patients who underwent follow-up chest computed tomography 18 months after COVID-19, abnormal findings remained at 51.9%. Males (odds ratio [OR], 0.17; 95% confidence interval [CI], 0.05–0.53; P=0.004) and elderly (OR, 1.04; 95% CI, 1.00–1.09; P=0.04) showed a significant association with long COVID after 12–18 months in a multivariable logistic regression analysis. Conclusion Many patients still showed long COVID after 18 months post SARS-CoV-2 infection. When managing these patients, the assessment of multiple aspects is necessary.

Background: The World Health Organization has declared the end of the coronavirus disease 2019 (COVID-19) public health emergency. However, this did not indicate the end of COVID-19. Several months after the infection, numerous patients complain of respiratory or nonspecific symptoms; this condition is called long COVID. Even patients with mild COVID-19 can experience long COVID, thus the burden of long COVID remains considerable. Therefore, we conducted this study to comprehensively analyze the effects of long COVID using multi-faceted assessments. Materials and Methods: We conducted a prospective cohort study involving patients diagnosed with COVID-19 between February 2020 and September 2021 in six tertiary hospitals in Korea. Patients were followed up at 1, 3, 6, 12, 18, and 24 months after discharge. Long COVID was defined as the persistence of three or more COVID-19-related symptoms. The primary outcome of this study was the prevalence of long COVID after the period of COVID-19. Results: During the study period, 290 patients were enrolled. Among them, 54.5 and 34.6% experienced long COVID within 6 months and after more than 18 months, respectively. Several patients showed abnormal results when tested for post-traumatic stress disorder (17.4%) and anxiety (31.9%) after 18 months. In patients who underwent follow-up chest computed tomography 18 months after COVID-19, abnormal findings remained at 51.9%. Males (odds ratio [OR], 0.17; 95% confidence interval [CI], 0.05–0.53; P=0.004) and elderly (OR, 1.04; 95% CI, 1.00–1.09; P=0.04) showed a significant association with long COVID after 12–18 months in a multivariable logistic regression analysis. Conclusion Many patients still showed long COVID after 18 months post SARS-CoV-2 infection. When managing these patients, the assessment of multiple aspects is necessary.

Background: Acute bronchiolitis is a common cause of hospitalization during infancy that carries significant morbidity and mortality rates.Purpose: This study compared the efficacy of different treatment modalities for infants with bronchiolitis in terms of hospital stay and clinical severity scores. Methods: The PubMed database was searched for relevant studies. Eligibility criteria included double-blind randomized controlled trial design, assessment of the effect of treatment on bronchiolitis in infants under 2 years of age, and publication in English from inception through July 31, 2020. The primary efficacy outcome was the length of hospital stay, while the secondary outcome was the clinical severity score. The standardized treatment effect and standard error of the effect size were calculated. Results: We identified 45 randomized controlled trials of 24 pairwise comparisons. These 45 trials included 5,061 participants and investigated 13 types of interventions (12 active, 1 placebo). Inhalation therapy with epinephrine (standard mean difference [SMD], -0.41; 95% confidence interval [CI], -0.8 to -0.03) and hypertonic saline (SMD, -0.29; 95% CI, -0.55 to -0.03) reduced the length of hospital stay compared with normal saline. Hypertonic saline was the most effective at improving the clinical severity score (SMD, -0.52; 95% CI, -0.95 to -0.10). Conclusion Inhalation therapy with epinephrine and hypertonic saline reduced the length of hospital stay and the clinical severity of bronchiolitis among infants under 2 years of age.

Background: Acute bronchiolitis is a common cause of hospitalization during infancy that carries significant morbidity and mortality rates.Purpose: This study compared the efficacy of different treatment modalities for infants with bronchiolitis in terms of hospital stay and clinical severity scores. Methods: The PubMed database was searched for relevant studies. Eligibility criteria included double-blind randomized controlled trial design, assessment of the effect of treatment on bronchiolitis in infants under 2 years of age, and publication in English from inception through July 31, 2020. The primary efficacy outcome was the length of hospital stay, while the secondary outcome was the clinical severity score. The standardized treatment effect and standard error of the effect size were calculated. Results: We identified 45 randomized controlled trials of 24 pairwise comparisons. These 45 trials included 5,061 participants and investigated 13 types of interventions (12 active, 1 placebo). Inhalation therapy with epinephrine (standard mean difference [SMD], -0.41; 95% confidence interval [CI], -0.8 to -0.03) and hypertonic saline (SMD, -0.29; 95% CI, -0.55 to -0.03) reduced the length of hospital stay compared with normal saline. Hypertonic saline was the most effective at improving the clinical severity score (SMD, -0.52; 95% CI, -0.95 to -0.10). Conclusion Inhalation therapy with epinephrine and hypertonic saline reduced the length of hospital stay and the clinical severity of bronchiolitis among infants under 2 years of age.

Background: Acute bronchiolitis is a common cause of hospitalization during infancy that carries significant morbidity and mortality rates.Purpose: This study compared the efficacy of different treatment modalities for infants with bronchiolitis in terms of hospital stay and clinical severity scores. Methods: The PubMed database was searched for relevant studies. Eligibility criteria included double-blind randomized controlled trial design, assessment of the effect of treatment on bronchiolitis in infants under 2 years of age, and publication in English from inception through July 31, 2020. The primary efficacy outcome was the length of hospital stay, while the secondary outcome was the clinical severity score. The standardized treatment effect and standard error of the effect size were calculated. Results: We identified 45 randomized controlled trials of 24 pairwise comparisons. These 45 trials included 5,061 participants and investigated 13 types of interventions (12 active, 1 placebo). Inhalation therapy with epinephrine (standard mean difference [SMD], -0.41; 95% confidence interval [CI], -0.8 to -0.03) and hypertonic saline (SMD, -0.29; 95% CI, -0.55 to -0.03) reduced the length of hospital stay compared with normal saline. Hypertonic saline was the most effective at improving the clinical severity score (SMD, -0.52; 95% CI, -0.95 to -0.10). Conclusion Inhalation therapy with epinephrine and hypertonic saline reduced the length of hospital stay and the clinical severity of bronchiolitis among infants under 2 years of age.

Background: Acute bronchiolitis is a common cause of hospitalization during infancy that carries significant morbidity and mortality rates.Purpose: This study compared the efficacy of different treatment modalities for infants with bronchiolitis in terms of hospital stay and clinical severity scores. Methods: The PubMed database was searched for relevant studies. Eligibility criteria included double-blind randomized controlled trial design, assessment of the effect of treatment on bronchiolitis in infants under 2 years of age, and publication in English from inception through July 31, 2020. The primary efficacy outcome was the length of hospital stay, while the secondary outcome was the clinical severity score. The standardized treatment effect and standard error of the effect size were calculated. Results: We identified 45 randomized controlled trials of 24 pairwise comparisons. These 45 trials included 5,061 participants and investigated 13 types of interventions (12 active, 1 placebo). Inhalation therapy with epinephrine (standard mean difference [SMD], -0.41; 95% confidence interval [CI], -0.8 to -0.03) and hypertonic saline (SMD, -0.29; 95% CI, -0.55 to -0.03) reduced the length of hospital stay compared with normal saline. Hypertonic saline was the most effective at improving the clinical severity score (SMD, -0.52; 95% CI, -0.95 to -0.10). Conclusion Inhalation therapy with epinephrine and hypertonic saline reduced the length of hospital stay and the clinical severity of bronchiolitis among infants under 2 years of age.

Cytomegalovirus (CMV) is the most important opportunistic viral pathogen in solid organ transplant (SOT) recipients.The Korean guideline for the prevention of CMV infection in SOT recipients was developed jointly by the Korean Society for Infectious Diseases and the Korean Society of Transplantation. CMV serostatus of both donors and recipients should be screened before transplantation to best assess the risk of CMV infection after SOT. Seronegative recipients receiving organs from seropositive donors face the highest risk, followed by seropositive recipients. Either antiviral prophylaxis or preemptive therapy can be used to prevent CMV infection. While both strategies have been demonstrated to prevent CMV infection post-transplant, each has its own advantages and disadvantages. CMV serostatus, transplant organ, other risk factors, and practical issues should be considered for the selection of preventive measures. There is no universal viral load threshold to guide treatment in preemptive therapy. Each institution should define and validate its own threshold.Valganciclovir is the favored agent for both prophylaxis and preemptive therapy. The evaluation of CMV-specific cellmediated immunity and the monitoring of viral load kinetics are gaining interest, but there was insufficient evidence to issue recommendations. Specific considerations on pediatric transplant recipients are included.

Background: The coronavirus disease 2019 (COVID-19) pandemic has caused the death of thousands of patients worldwide. Although age is known to be a risk factor for morbidity and mortality in COVID-19 patients, critical illness or death is occurring even in the younger age group as the epidemic spreads. In early 2022, omicron became the dominant variant of the COVID-19 virus in South Korea, and the epidemic proceeded on a large scale. Accordingly, this study aimed to determine whether young adults (aged ≤ 50 years) with critical COVID-19 infection during the omicron period had different characteristics from older patients and to determine the risk factors for mortality in this specific age group. Methods: We evaluated 213 critical adult patients (high flow nasal cannula or higher respiratory support) hospitalized for polymerase chain reaction-confirmed COVID-19 in nine hospitals in South Korea between February 1, 2022 and April 30, 2022. Demographic characteristics, including body mass index (BMI) and vaccination status; underlying diseases; clinical features and laboratory findings; clinical course; treatment received; and outcomes were collected from electronic medical records (EMRs) and analyzed according to age and mortality. Results: Overall, 71 critically ill patients aged ≤ 50 years were enrolled, and 142 critically ill patients aged over 50 years were selected through 1:2 matching based on the date of diagnosis. The most frequent underlying diseases among those aged ≤ 50 years were diabetes and hypertension, and all 14 patients who died had either a BMI ≥ 25 kg/m 2 or an underlying disease. The total case fatality rate among severe patients (S-CFR) was 31.0%, and the S-CFR differed according to age and was higher than that during the delta period. The S-CFR was 19.7% for those aged ≤ 50 years, 36.6% for those aged > 50 years, and 38.1% for those aged ≥ 65 years. In multivariate analysis, age (odds ratio [OR], 1.084; 95% confidence interval [CI], 1.043–1.127), initial low-density lipoprotein > 600 IU/L (OR, 4.782; 95% CI, 1.584–14.434), initial C-reactive protein > 8 mg/dL (OR, 2.940; 95% CI, 1.042–8.293), highest aspartate aminotransferase > 200 IU/L (OR, 12.931; 95% CI, 1.691–98.908), and mechanical ventilation implementation (OR, 3.671; 95% CI, 1.294–10.420) were significant independent predictors of mortality in critical COVID-19 patients during the omicron wave. A similar pattern was shown when analyzing the data by age group, but most had no statistical significance owing to the small number of deaths in the young critical group. Although the vaccination completion rate of all the patients (31.0%) was higher than that in the delta wave period (13.6%), it was still lower than that of the general population. Further, only 15 (21.1%) critically ill patients aged ≤ 50 years were fully vaccinated. Overall, the severity of hospitalized critical patients was significantly higher than that in the delta period, indicating that it was difficult to find common risk factors in the two periods only with a simple comparison. Conclusion Overall, the S-CFR of critically ill COVID-19 patients in the omicron period was higher than that in the delta period, especially in those aged ≤ 50 years. All of the patients who died had an underlying disease or obesity. In the same population, the vaccination rate was very low compared to that in the delta wave, indicating that non-vaccination significantly affected the progression to critical illness. Notably, there was a lack of prescription for Paxlovid for these patients although they satisfied the prescription criteria. Early diagnosis and active initial treatment was necessary, along with the proven methods of vaccination and personal hygiene. Further studies are needed to determine how each variant affects critically ill patients.

Background: Numerous patients around the globe are dying from coronavirus disease 2019 (COVID-19). While age is a known risk factor, risk analysis in the young generation is lacking. The present study aimed to evaluate the clinical features and mortality risk factors in younger patients (≤ 50 years) with a critical case of COVID-19 in comparison with those among older patients (> 50 years) in Korea. Methods: We analyzed the data of adult patients only in critical condition (requiring high flow nasal cannula oxygen therapy or higher respiratory support) hospitalized with PCR-confirmed COVID-19 at 11 hospitals in Korea from July 1, 2021 to November 30, 2021 when the delta variant was a dominant strain. Patients’ electronic medical records were reviewed to identify clinical characteristics. Results: During the study period, 448 patients were enrolled. One hundred and forty-two were aged 50 years or younger (the younger group), while 306 were above 50 years of age (the older group). The most common pre-existing conditions in the younger group were diabetes mellitus and hypertension, and 69.7% of the patients had a body mass index (BMI) > 25 kg/m 2 .Of 142 younger patients, 31 of 142 patients (21.8%, 19 women) did not have these pre-existing conditions. The overall case fatality rate among severity cases was 21.0%, and it differed according to age: 5.6% (n = 8/142) in the younger group, 28.1% in the older group, and 38% in the ≥ 65 years group. Age (odds ratio [OR], 7.902; 95% confidence interval [CI], 2.754–18.181), mechanical ventilation therapy (OR, 17.233; 95% CI, 8.439–35.192), highest creatinine > 1.5 mg/dL (OR, 17.631; 95% CI, 8.321–37.357), and combined blood stream infection (OR, 7.092;95% CI, 1.061–18.181) were identified as independent predictors of mortality in total patients.Similar patterns were observed in age-specific analyses, but most results were statistically insignificant in multivariate analysis due to the low number of deaths in the younger group.The full vaccination rate was very low among study population (13.6%), and only three patients were fully vaccinated, with none of the patients who died having been fully vaccinated in the younger group. Seven of eight patients who died had a pre-existing condition or were obese (BMI > 25 kg/m 2 ), and the one remaining patient died from a secondary infection. Conclusion About 22% of the patients in the young critical group did not have an underlying disease or obesity, but the rate of obesity (BMI > 25 kg/m2 ) was high, with a fatality rate of 5.6%. The full vaccination rate was extremely low compared to the general population of the same age group, showing that non-vaccination has a grave impact on the progression of COVID-19 to a critical condition. The findings of this study highlight the need for measures to prevent critical progression of COVID-19, such as vaccinations and targeting young adults especially having risk factors.