Time from Exposure to Diagnosis among Quarantined Close Contacts of SARS-CoV-2 Omicron Variant Index Case-Patients, South Korea.

To determine optimal quarantine duration, we evaluated time from exposure to diagnosis for 107 close contacts of severe acute respiratory syndrome coronavirus 2 Omicron variant case-patients. Average time from exposure to diagnosis was 3.7 days; 70% of diagnoses were made on day 5 and 99.1% by day 10, suggesting 10-day quarantine.

Community Transmission of SARS-CoV-2 Omicron Variant, South Korea, 2021.

In South Korea, a November 2021 outbreak caused by severe acute respiratory syndrome coronavirus 2 Omicron variant originated from 1 person with an imported case and spread to households, kindergartens, workplaces, restaurants, and hospitals, resulting in 11 clusters within 3 weeks. An epidemiologic curve indicated rapid community transmission of the Omicron variant.

Pathophysiological role of endogenous irisin against tumorigenesis and metastasis: Is it a potential biomarker and therapeutic?

In the last few decades, there has been notable progress in understanding the molecular and cellular basis of the complex process involved in cancer. In this context, tumor-promoting inflammation, dysregulation of apoptotic signaling, tissue invasion and metastasis, and cancer microenvironment have recently attracted interest from researchers. Irisin is a hormone released by muscles during exercise and it directly acts on key functional cells involving energy metabolism and homeostasis. Recently, many studies have reported the anticancer effect of irisin against different types of cancer. Translation of these findings to clinical practice for the diagnosis and treatment of several types of cancer is urgently required. In this review, we summarized preclinical and clinical studies on the anticancer effects of irisin in various types of cancer, and also discussed the mechanisms activated by irisin to suppress cancer pathogenesis. We further discussed the serum level of irisin related to different types of cancer to understand more clearly the association between irisin concentration and tumor burden. This review may serve as a solid foundation for researchers and physicians to support basic and clinical studies on irisin as a promising strategy for early diagnosis and treatment of a various types of cancers.

Evaluation of the acute hepatitis B surveillance system in the Republic of Korea following the transition to mandatory surveillance.

BACKGROUND: The prevalence of hepatitis B in the Republic of Korea has declined, yet the disease burden persists. After various changes in targets and methods, the national hepatitis B surveillance system now exclusively monitors acute cases. We aimed to assess the alignment of this system with its intended purpose and to recommend improvements supporting the national strategic plan for viral hepatitis management. METHODS: This study assessed acute hepatitis B cases reported to the Korean Disease Control and Prevention Agency's mandatory surveillance system over a 10-year period (2013-2022). It evaluated 5 factors from the Centers for Disease Control and Prevention's Updated Guidelines for Evaluating Public Health Surveillance Systems: simplicity, positive predictive value, data quality, timeliness, and usefulness. RESULTS: The nonspecific nature of acute hepatitis B symptoms, along with the complexity of diagnostic criteria, indicated a high potential for misreporting. The surveillance system demonstrated a high positive predictive value (94.4%), with data quality and timeliness also rated high. However, data following the onset of the coronavirus disease 2019 pandemic indicate the need for improvement. Moreover, given the relative importance of specific characteristics of chronic infectious diseases, only limited interventions are implementable through the current surveillance system. CONCLUSION: The evaluation of the Republic of Korea's acute hepatitis B surveillance system revealed high positive predictive value, data quality, and timeliness. However, improvements can be made in the misreporting of chronic cases and the system's usefulness. More accurate reflection of the characteristics of acute hepatitis B cases is essential for better management of viral hepatitis.

Characteristics of a large outbreak arising from a school field trip after COVID-19 restrictions were eased in 2022.

BACKGROUND: This study analyzed a large outbreak of coronavirus disease 2019 (COVID-19) that occurred during a high school field trip in the Jeonbuk region and aimed to identify risk factors for COVID-19 infection, with the goal of preventing such outbreaks in the future. METHODS: A retrospective cohort study of 737 participants, including 668 students and 69 staff at High School A, was designed to describe the epidemiological characteristics of this large COVID-19 outbreak. Logistic regression analysis was performed to calculate relative risks (odds ratios [ORs]) and 95% confidence intervals (CIs). RESULTS: There were 190 confirmed cases (174 students, 16 staff), with an attack rate of 25.8%. Small outbreaks were decreasing before the field trip, but this trend reversed after the trip, leading to larger outbreaks. Logistic regression showed an OR of 2.39 (95% CI, 1.66-3.43; p<0.05) for COVID-19 infection among field trip participants. Among them, 11th graders had an OR of 2.32 (95% CI, 1.53-3.52; p<0.05) compared to 10th graders, while no significant risk difference was found within same-grade teams. CONCLUSION: There was a high risk for COVID-19 transmission during extracurricular activities with a large number of participants, such as field trips, even after the nationwide Omicron variant epidemic subsided. Even when students are separated into teams and follow different routes, it is challenging to design routes that entirely prevent contact between teams. Thus, programs should be designed carefully, and students with symptoms should be identified before and during the program to isolate them promptly.

A Seroprevalence Study on Residents in a Senior Care Facility with Breakthrough SARS-CoV-2 Omicron Infection.

The Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began spreading rapidly in the community in November 2021, becoming the dominant variant in the Republic of Korea in 2022. Although its pathogenesis in healthy individuals was low, the severity and hospitalization rate was higher in the elderly and immunocompromised patients. We aimed to investigate the immunogenicity in acute and convalescent phases of breakthrough infection by Omicron in elderly individuals. Serological data were assessed by electrochemiluminescence immunoassay, enzyme-linked immunosorbent assay, and plaque-reduction neutralization tests. SARS-CoV-2-specific antibody and immunoglobulin G levels in the acute phase were higher in third dose-vaccinated elderly than in first and second dose-vaccinated patients. The neutralization antibody titer was detected only in third dose-vaccinated patients, and the titer was higher for the Delta than the Omicron variant. In the convalescent phase of Omicron infection, the neutralization antibody titer of vaccinated patients was higher for the Delta than the Omicron variant except in unvaccinated individuals. We demonstrated that the cause of the vulnerability to Omicron variant infection in third dose-vaccinated elderly was due to the low neutralization antibody level against Omicron. A fourth dose of vaccination is required in the elderly to reduce hospitalization and mortality caused by the Omicron variant.