OBJECTIVES: We estimated the population prevalence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including unreported infections, through a Korea Seroprevalence Study of Monitoring of SARS-CoV-2 Antibody Retention and Transmission (K-SEROSMART) in 258 communities throughout Korea. METHODS: In August 2022, a survey was conducted among 10,000 household members aged 5 years and older, in households selected through two stage probability random sampling. During face-to-face household interviews, participants self-reported their health status, COVID-19 diagnosis and vaccination history, and general characteristics. Subsequently, participants visited a community health center or medical clinic for blood sampling. Blood samples were analyzed for the presence of antibodies to spike proteins (anti-S) and antibodies to nucleocapsid proteins (anti-N) SARS-CoV-2 proteins using an electrochemiluminescence immunoassay. To estimate the population prevalence, the PROC SURVEYMEANS statistical procedure was employed, with weighting to reflect demographic data from July 2022. RESULTS: In total, 9,945 individuals from 5,041 households were surveyed across 258 communities, representing all basic local governments in Korea. The overall population-adjusted prevalence rates of anti-S and anti-N were 97.6% and 57.1%, respectively. Since the Korea Disease Control and Prevention Agency has reported a cumulative incidence of confirmed cases of 37.8% through July 31, 2022, the proportion of unreported infections among all COVID-19 infection was suggested to be 33.9%. CONCLUSIONS The K-SEROSMART represents the first nationwide, community-based seroepidemiologic survey of COVID-19, confirming that most individuals possess antibodies to SARS-CoV-2 and that a significant number of unreported cases existed. Furthermore, this study lays the foundation for a surveillance system to continuously monitor transmission at the community level and the response to COVID-19.

This study aimed to investigate the association between Bacille Calmette-Guérin (BCG) vaccination and nontuberculous mycobacterial pulmonary disease (NTM-PD). Patients in the prospective NTM-PD cohort were matched to healthy controls to measure the association between BCG and NTM-PD development. The clinical course of NTM-PD patients was also evaluated to investigate the association between BCG and NTM-PD progression. BCG scars were not associated with NTM-PD development (adjusted odds ratio [OR], 2.04; 95% confidence interval [CI], 0.96–4.34) or progression (adjusted OR, 1.61; 95% CI, 0.92–2.81).In conclusion, BCG vaccination was not associated with the development or progression of NTM-PD.

Background: In 2017, Korea implemented nationwide latent tuberculosis infection (LTBI) project targeting healthcare workers (HCWs). We aimed to assess its performance using the cascade of care model. Methods: We included 45,503 employees of medical institutions with positive interferongamma release assay result who participated between March 2017 and December 2018. We described percentages of LTBI participants completing each step in the cascade of care.Poisson regression model was conducted to assess individual characteristics and factors associated with not-visiting clinics for further care, not-initiating LTBI treatment, and notcompleting treatment. Results: Proportions of visiting clinics and initiating and completing treatment in HCWs were 54.9%, 38.5%, and 32.0%, respectively. Despite of less likelihood of visiting clinics and initiating LTBI treatment, older age ≥ 65 years were more likely to complete treatment (adjusted relative risk [aRR], 0.80; 95% confidence interval [CI], 0.64–0.99), compared to young age < 35 years. Compared to nurses, doctors were less likely to visit clinic; however, were more likely to initiate treatment (aRR, 0.88; 95% CI, 0.81–0.96). Those who visited public health centers were associated with not-initiating treatment (aRR, 1.34; 95% CI, 1.29–1.40). When treated at private hospitals, 9-month isoniazid monotherapy was less likely to complete treatment, compared to 3-month isoniazid and rifampicin combination therapy (aRR, 1.33; 95% CI, 1.16–1.53). Conclusion Among employees of medical institutions with LTBI, only one third completed treatment. Age, occupation, treatment center, and initial regimen were significantly related to LTBI treatment performance indicators. Rifampicin-based short treatment regimens were effective under standard of care.

Background/Aims: Besifovir dipivoxil maleate (BSV), an acyclic nucleotide phosphonate, shows potent antiviral activity against hepatitis B virus. Our previous 48-week trial revealed that BSV has comparable antiviral efficacy to tenofovir disoproxil fumarate (TDF) and better safety profiles in terms of improved renal and bone safety. This extension study evaluated the prolonged efficacy and safety of BSV in treatment-naive chronic hepatitis B patients. Methods: Patients continued to participate in an open-label BSV study after an initial 48-week double-blind comparison of BSV and TDF treatment. The antiviral efficacy and drug safety was evaluated up to 192 weeks in two groups: patients continuing BSV treatment (BSV-BSV) and patients switching from TDF to BSV after 48 weeks (TDF-BSV). Results: Among 197 patients receiving randomized treatments, 170 (86%) entered the open-label phase and 152 (77%) entered the 192-week extension study. Virological response rates over 192 weeks were 92.50% and 93.06% in the BSV-BSV and TDF-BSV groups, respectively (P=0.90). Hepatitis B envelop antigen seroconversion and alanine aminotransferase normalization rates were similar between the groups (P=0.75 and P=0.36, respectively). There were no drug-resistant mutations to BSV. Bone mineral density and renal function were well preserved in the BSV-BSV group, whereas these initially worsened then recovered after switching therapy in the TDF-BSV group. Conclusions BSV maintained potent antiviral efficacy after 192 weeks and showed no evidence of drug resistance. BSV was safe, well tolerated, and effective in patients who switched from TDF to BSV. Trial Registration Number: NCT01937806 (date: 10 Sep 2013).

In 2017, the Korean government launched an unprecedentedly large-scaled latent tuberculosis infection (LTBI) screening project which covered more than a million individuals in congregate settings. A total of 1,047,689 participants of source population (n = 2,336,157) underwent LTBI testing from 2017 to 2018. The overall LTBI test uptake rate during this project was 44.8%. Workers in daycare centers (83.5%) and kindergartens (78.9%) showed high participation rate. A total of 1,012,206 individuals with valid results of interferongamma release assay (IGRA) were selected to constitute the IGRA cohort. Most of the enrolled participants in the IGRA cohort were in their working age. Approximately, threequarters of total enrolled population were female. Investigating the LTBI prevalence, stages of LTBI care cascade, natural history of LTBI, efficacy of LTBI treatment and cost-effectiveness of LTBI screening are feasible within this IGRA cohort.

In 2017, the Korean government launched an unprecedentedly large-scaled latent tuberculosis infection (LTBI) screening project which covered more than a million individuals in congregate settings. A total of 1,047,689 participants of source population (n = 2,336,157) underwent LTBI testing from 2017 to 2018. The overall LTBI test uptake rate during this project was 44.8%. Workers in daycare centers (83.5%) and kindergartens (78.9%) showed high participation rate. A total of 1,012,206 individuals with valid results of interferongamma release assay (IGRA) were selected to constitute the IGRA cohort. Most of the enrolled participants in the IGRA cohort were in their working age. Approximately, threequarters of total enrolled population were female. Investigating the LTBI prevalence, stages of LTBI care cascade, natural history of LTBI, efficacy of LTBI treatment and cost-effectiveness of LTBI screening are feasible within this IGRA cohort.

A 60-year-old man diagnosed with unresectable hepatocellular carcinoma (HCC) presented to the hospital with pain in the perineal region. He had been taking lenvatinib every day for 2 months after he was diagnosed with HCC with metastases to the lymph node, small bowel mesentery, and retroperitoneal space. Enhanced abdominal computed tomography revealed mild elevation in intensity in the perineal subcutaneous tissue with subcutaneous emphysema. The patient was diagnosed with Common Terminology Criteria for Adverse Events grade 3, skin ulceration of stage IV with full-thickness skin loss and tissue necrosis in the muscular layer. The patient was taken off the medication with prescription of antibiotics, and after 3 weeks, the skin has fully recovered. This is the first report of an HCC patient who presented with a skin ulceration of stage IV after lenvatinib treatment. We recommend stopping the medication immediately and changing to alternative treatments with appropriate supportive care.

A 60-year-old man diagnosed with unresectable hepatocellular carcinoma (HCC) presented to the hospital with pain in the perineal region. He had been taking lenvatinib every day for 2 months after he was diagnosed with HCC with metastases to the lymph node, small bowel mesentery, and retroperitoneal space. Enhanced abdominal computed tomography revealed mild elevation in intensity in the perineal subcutaneous tissue with subcutaneous emphysema. The patient was diagnosed with Common Terminology Criteria for Adverse Events grade 3, skin ulceration of stage IV with full-thickness skin loss and tissue necrosis in the muscular layer. The patient was taken off the medication with prescription of antibiotics, and after 3 weeks, the skin has fully recovered. This is the first report of an HCC patient who presented with a skin ulceration of stage IV after lenvatinib treatment. We recommend stopping the medication immediately and changing to alternative treatments with appropriate supportive care.

Background/Aims: Besifovir dipivoxil maleate (BSV), an acyclic nucleotide phosphonate, shows potent antiviral activity against hepatitis B virus. Our previous 48-week trial revealed that BSV has comparable antiviral efficacy to tenofovir disoproxil fumarate (TDF) and better safety profiles in terms of improved renal and bone safety. This extension study evaluated the prolonged efficacy and safety of BSV in treatment-naive chronic hepatitis B patients. Methods: Patients continued to participate in an open-label BSV study after an initial 48-week double-blind comparison of BSV and TDF treatment. The antiviral efficacy and drug safety was evaluated up to 192 weeks in two groups: patients continuing BSV treatment (BSV-BSV) and patients switching from TDF to BSV after 48 weeks (TDF-BSV). Results: Among 197 patients receiving randomized treatments, 170 (86%) entered the open-label phase and 152 (77%) entered the 192-week extension study. Virological response rates over 192 weeks were 92.50% and 93.06% in the BSV-BSV and TDF-BSV groups, respectively (P=0.90). Hepatitis B envelop antigen seroconversion and alanine aminotransferase normalization rates were similar between the groups (P=0.75 and P=0.36, respectively). There were no drug-resistant mutations to BSV. Bone mineral density and renal function were well preserved in the BSV-BSV group, whereas these initially worsened then recovered after switching therapy in the TDF-BSV group. Conclusions BSV maintained potent antiviral efficacy after 192 weeks and showed no evidence of drug resistance. BSV was safe, well tolerated, and effective in patients who switched from TDF to BSV. Trial Registration Number: NCT01937806 (date: 10 Sep 2013).

Background/Aims: To improve the eradication rate of a first-line therapy for Helicobacter pylori infection, alternate regimens such as sequential, concomitant, and hybrid therapies have been tried. The aim of this study was to evaluate the eradication rate of the 10-day hybrid therapy as a first-line therapy. Materials and Methods: This retrospective study enrolled 124 patients from the Korea University Ansan Hospital between April 2016 and December 2019. The 10-day hybrid therapy comprised 5 days of dual therapy (proton pump inhibitor [PPI] standard dose and amoxicillin 1 g, twice daily) followed by 5 days of quadruple therapy (PPI, amoxicillin 1 g, clarithromycin 500 mg, and metronidazole 500 mg, twice daily). We compared the 10-day hybrid therapy with the 10-day concomitant therapy comprising PPI, amoxicillin 1 g, clarithromycin 500 mg, and metronidazole 500 mg, twice daily. Eradication was assessed by a 13C-urea breath test or gastroscopic biopsy at least 4 weeks after treatment completion. Results: The eradication rates of the 10-day hybrid and concomitant therapies were 74.2% (46/62) and 67.7% (42/62), respectively, in the intention-to-treat (ITT) analysis and 88.5% (46/52) and 82.4% (42/51), respectively, in the per-protocol (PP) analysis. There was no significant difference in the eradication rates between the two groups in the ITT (P=0.429) and PP analysis (P=0.380). Adverse events developed in 75.0% and 70.6% of patients in the hybrid and concomitant groups, respectively, but there was no significant difference (P=0.615). Conclusions The 10-day hybrid therapy can be an option for a first-line therapy of Helicobacter pylori infection.