Immune Responses After Vaccination With Primary 2-Dose ChAdOx1 Plus a Booster of BNT162b2 or Vaccination With Primary 2-Dose BNT162b2 Plus a Booster of BNT162b2 and the Occurrence of Omicron Breakthrough Infection

Background@#Before the omicron era, health care workers were usually vaccinated with either the primary 2-dose ChAdOx1 nCoV-19 (Oxford-AstraZeneca) series plus a booster dose of BNT162b2 (Pfizer-BioNTech) (CCB group) or the primary 2-dose BNT162b2 series plus a booster dose of BNT162b2 (BBB group) in Korea. @*Methods@#The two groups were compared using quantification of the surrogate virus neutralization test for wild type severe acute respiratory syndrome coronavirus 2 (SVNT-WT), the omicron variant (SVNT-O), spike-specific IgG, and interferon-gamma (IFN-γ), as well as the omicron breakthrough infection cases. @*Results@#There were 113 participants enrolled in the CCB group and 51 enrolled in the BBB group. Before and after booster vaccination, the median SVNT-WT and SVNT-O values were lower in the CCB (SVNT-WT [before-after]: 72.02–97.61%, SVNT-O: 15.18–42.29%) group than in the BBB group (SVNT-WT: 89.19–98.11%, SVNT-O: 23.58–68.56%; all P < 0.001). Although the median IgG concentrations were different between the CCB and BBB groups after the primary series (2.677 vs. 4.700 AU/mL, respectively, P < 0.001), they were not different between the two groups after the booster vaccination (7.246 vs. 7.979 AU/mL, respectively, P = 0.108). In addition, the median IFN-γ concentration was higher in the BBB group than in the CCB group (550.5 and 387.5 mIU/mL, respectively, P = 0.014). There was also a difference in the cumulative incidence curves over time (CCB group 50.0% vs. BBB group 41.8%; P = 0.045), indicating that breakthrough infection occurred faster in the CCB group. @*Conclusion@#The cellular and humoral immune responses were low in the CCB group so that the breakthrough infection occurred faster in the CCB group than in the BBB group.

Positivity of Rapid Antigen Testing for SARS-CoV-2 With Serial Followed-up Nasopharyngeal Swabs in Hospitalized Patients due to COVID-19

Despite the accuracy of nucleic acid amplification tests (NAATs), rapid antigen tests (RATs) for severe acute respiratory syndrome coronavirus-2 are widely used as point-of-care tests. A total of 282 pairs of reverse transcription-polymerase chain reaction and Standard Q COVID-19 Ag tests were serially conducted for 68 patients every 3–4 days until their discharge. Through a field evaluation of RATs using direct nasopharyngeal swabs, the sensitivities were 84.6% and 87.3% for E and RNA-dependent RNA polymerase (RdRp) genes, respectively, for specimens with cycle thresholds (Cts) < 25. The Ct values of E and RdRp genes for 95% detection rates by RATs were 16.9 and 18.1, respectively. The sensitivity of RAT was 48.4% after the onset of symptoms, which was not sufficient. RAT positivity gradually decreased with increased time after symptom onset and had continuously lower sensitivity than NAATs.

Rhinovirus Incidence Rates Indicate We Are Tired of Non-pharmacological Interventions Against Coronavirus Disease 2019

Background@#During the coronavirus disease 2019 (COVID-19) pandemic, the incidence of rhinovirus (RV) is inversely related to the intensity of non-pharmacological interventions (NPIs), such as universal mask wearing and physical distancing. @*Methods@#Using RV surveillance data, changes in the effect of NPIs were investigated in South Korea during the pandemic. The time to the first visible effect of NPIs after the onset of NPIs (T1), time to the maximum effect (T2), and duration of the maximum effect (T3) were measured for each surge. For each week, the RVdiff [(RV incidence during the pandemic) − (RV incidence within 5 years before the pandemic)] was calculated, and number of weeks for RVdiff to be below zero after NPIs (time to RVdiff ≤ 0) and number of weeks RVdiff remains below zero after NPIs (duration of RVdiff ≤ 0) were measured for each surge. @*Results@#During the study period, four surges of COVID-19 were reported. As the pandemic progressed, T1 and T2 increased, but T3 decreased. Additionally, the “time to RVdiff of ≤ 0” increased and “duration of RVdiff of ≤ 0” decreased. These changes became more pronounced during the third surge (mid-November 2020), before the introduction of the COVID-19 vaccine, and from the emergence of the delta variant. @*Conclusion@#The effect of NPIs appears slower, the duration of the effect becomes shorter, and the intensity also decreases less than a year after the onset of the pandemic owing to people’s exhaustion in implementing NPIs. These findings suggest that the COVID-19 response strategy must be completely overhauled

Machine-Learning-Based Approach to Differential Diagnosis in Tuberculous and Viral Meningitis / 감염과화학요법

Background@#Tuberculous meningitis (TBM) is the most severe form of tuberculosis, but differentiating between the diagnosis of TBM and viral meningitis (VM) is difficult. Thus, we have developed machine-learning modules for differentiating TBM from VM.Material and Methods: For the training data, confirmed or probable TBM and confirmed VM cases were retrospectively collected from five teaching hospitals in Korea between January 2000 - July 2018. Various machine-learning algorithms were used for training. The machinelearning algorithms were tested by the leave-one-out cross-validation. Four residents and two infectious disease specialists were tested using the summarized medical information. @*Results@#The training study comprised data from 60 patients with confirmed or probable TBM and 143 patients with confirmed VM. Older age, longer symptom duration before the visit, lower serum sodium, lower cerebrospinal fluid (CSF) glucose, higher CSF protein, and CSF adenosine deaminase were found in the TBM patients. Among the various machinelearning algorithms, the area under the curve (AUC) of the receiver operating characteristics of artificial neural network (ANN) with ImperativeImputer for matrix completion (0.85; 95% confidence interval 0.79 - 0.89) was found to be the highest. The AUC of the ANN model was statistically higher than those of all the residents (range 0.67 - 0.72, P <0.001) and an infectious disease specialist (AUC 0.76; P = 0.03). @*Conclusion@#The machine-learning techniques may play a role in differentiating between TBM and VM. Specifically, the ANN model seems to have better diagnostic performance than the non-expert clinician.

Machine-Learning-Based Approach to Differential Diagnosis in Tuberculous and Viral Meningitis / 감염과화학요법

Background@#Tuberculous meningitis (TBM) is the most severe form of tuberculosis, but differentiating between the diagnosis of TBM and viral meningitis (VM) is difficult. Thus, we have developed machine-learning modules for differentiating TBM from VM.Material and Methods: For the training data, confirmed or probable TBM and confirmed VM cases were retrospectively collected from five teaching hospitals in Korea between January 2000 - July 2018. Various machine-learning algorithms were used for training. The machinelearning algorithms were tested by the leave-one-out cross-validation. Four residents and two infectious disease specialists were tested using the summarized medical information. @*Results@#The training study comprised data from 60 patients with confirmed or probable TBM and 143 patients with confirmed VM. Older age, longer symptom duration before the visit, lower serum sodium, lower cerebrospinal fluid (CSF) glucose, higher CSF protein, and CSF adenosine deaminase were found in the TBM patients. Among the various machinelearning algorithms, the area under the curve (AUC) of the receiver operating characteristics of artificial neural network (ANN) with ImperativeImputer for matrix completion (0.85; 95% confidence interval 0.79 - 0.89) was found to be the highest. The AUC of the ANN model was statistically higher than those of all the residents (range 0.67 - 0.72, P <0.001) and an infectious disease specialist (AUC 0.76; P = 0.03). @*Conclusion@#The machine-learning techniques may play a role in differentiating between TBM and VM. Specifically, the ANN model seems to have better diagnostic performance than the non-expert clinician.

Immunoglobulin G4-Related Gastric Ulcer Mimicking Advanced Stomach Cancer in a Patient with Type I Autoimmune Pancreatitis / 대한내과학회지

Type I autoimmune pancreatitis (AIP), a form of chronic pancreatitis, is included within the spectrum of immunoglobulin G4-related diseases (IgG4-RD). IgG4-RD can involve the salivary glands, bile ducts, kidneys and retroperitoneum, and the pancreas, and responds well to corticosteroid treatment. However, gastric involvement in IgG4-RD has been rarely reported. Here we report the case of a 56-year-old man with type I autoimmune pancreatitis who presented with a giant gastric ulcer mimicking advanced gastric cancer, which was subsequently determined to be IgG4-RD. Both the patient' symptoms and his ulcerative lesions in the stomach responded to steroid treatment, which obviated the need for major surgery such as gastrectomy. Our case demonstrates the importance of recognizing potential gastric involvement in IgG4-RD, especially in a patient with concurrent AIP/IgG4-RD or a history of the disease, who is evaluated for an intractable and/or atypical gastric ulcer. A prompt diagnosis and proper management will avoid unnecessary surgery.

Malignant Melanoma of the Pancreas and Liver Mimicking a Neuroendocrine Tumor / 대한내과학회지

Among metastatic pancreatic tumors, malignant melanomas are rare. Here, we report a very rare case of a malignant melanoma that involved only the pancreas and liver, and was difficult to differentiate from a neuroendocrine tumor of the pancreas with a liver metastasis. A 65-year-old- male with no history of a malignant melanoma exhibited hypervascular hepatic and pancreatic tumors on computed tomography and contrast-enhanced endoscopic ultrasonography. He lacked lesions of the skin, eye, and gastrointestinal tract on physical examination, upper endoscopy, and a whole-body positron emission tomography-computed tomography scan; these sites are common primary sites of malignant melanoma. Finally, endoscopic ultrasound-guided pancreatic core biopsy and percutaneous ultrasonography-guided liver biopsy confirmed malignant melanoma of the pancreas and liver.

Pancreatic Neuroendocrine Tumor with Primary Hepatic B Cell Lymphoma / 대한내과학회지

Pancreatic neuroendocrine tumors (NETs) frequently accompany metastatic lesions, and hepatic metastases are the most common of all NETs. However, another disease may also be present, potentially leading to misdiagnosis and metastasis of a NET. Clinicians should consider an active diagnostic evaluation for metastatic lesions, including liver biopsy, particularly when the hepatic lesion has distinct characteristics from the primary tumor. In our case, the patient had both a pancreatic NET and a primary hepatic lymphoma. She underwent laparoscopic distal pancreatectomy with splenectomy, and progress of the primary hepatic lymphoma was observed in the outpatient clinic.

Immunoglobulin G4-Related Gastric Ulcer Mimicking Advanced Stomach Cancer in a Patient with Type I Autoimmune Pancreatitis / 대한내과학회지

Type I autoimmune pancreatitis (AIP), a form of chronic pancreatitis, is included within the spectrum of immunoglobulin G4-related diseases (IgG4-RD). IgG4-RD can involve the salivary glands, bile ducts, kidneys and retroperitoneum, and the pancreas, and responds well to corticosteroid treatment. However, gastric involvement in IgG4-RD has been rarely reported. Here we report the case of a 56-year-old man with type I autoimmune pancreatitis who presented with a giant gastric ulcer mimicking advanced gastric cancer, which was subsequently determined to be IgG4-RD. Both the patient' symptoms and his ulcerative lesions in the stomach responded to steroid treatment, which obviated the need for major surgery such as gastrectomy. Our case demonstrates the importance of recognizing potential gastric involvement in IgG4-RD, especially in a patient with concurrent AIP/IgG4-RD or a history of the disease, who is evaluated for an intractable and/or atypical gastric ulcer. A prompt diagnosis and proper management will avoid unnecessary surgery.

Pancreatic Neuroendocrine Tumor with Primary Hepatic B Cell Lymphoma / 대한내과학회지

Pancreatic neuroendocrine tumors (NETs) frequently accompany metastatic lesions, and hepatic metastases are the most common of all NETs. However, another disease may also be present, potentially leading to misdiagnosis and metastasis of a NET. Clinicians should consider an active diagnostic evaluation for metastatic lesions, including liver biopsy, particularly when the hepatic lesion has distinct characteristics from the primary tumor. In our case, the patient had both a pancreatic NET and a primary hepatic lymphoma. She underwent laparoscopic distal pancreatectomy with splenectomy, and progress of the primary hepatic lymphoma was observed in the outpatient clinic.

Malignant Melanoma of the Pancreas and Liver Mimicking a Neuroendocrine Tumor / 대한내과학회지

Among metastatic pancreatic tumors, malignant melanomas are rare. Here, we report a very rare case of a malignant melanoma that involved only the pancreas and liver, and was difficult to differentiate from a neuroendocrine tumor of the pancreas with a liver metastasis. A 65-year-old- male with no history of a malignant melanoma exhibited hypervascular hepatic and pancreatic tumors on computed tomography and contrast-enhanced endoscopic ultrasonography. He lacked lesions of the skin, eye, and gastrointestinal tract on physical examination, upper endoscopy, and a whole-body positron emission tomography-computed tomography scan; these sites are common primary sites of malignant melanoma. Finally, endoscopic ultrasound-guided pancreatic core biopsy and percutaneous ultrasonography-guided liver biopsy confirmed malignant melanoma of the pancreas and liver.