Diagnostic Performance of Interferon Gamma Release Assay (IGRA) for Cell-Mediated Immune Responses to SARS-CoV-2.

BACKGROUND: As SARS-CoV-2 infection became a pandemic, much effort has been made to measure both antibody production and T cell response to SARS-CoV-2 to diagnose COVID-19 patients or find out their immune status. Authors tried to determine the optimal cutoff value and evaluate clinical performance of one interferon-γ release assay (IGRA) kit and compared their results with serological antibody assay in COVID-19 patients. METHODS: Study subjects included 100 patients confirmed as COVID-19 with RT-PCR method and 88 healthy volunteers who were PCR negative. IGRA tests were performed using STANDARDTM E Covi-FERON ELISA. Presence of SARS-CoV-2 antibodies was detected using STANDARD Q COVID-19 IgM/IgG Plus Test. Cutoff value was assessed using receiver operating characteristic (ROC) curve. RESULTS: The cutoff value was 0.24 IU/mL and the area under the curve (AUC) of the ROC curve was 0.973 with 95% confidence interval (CI) of 0.940 - 1.005. At this cutoff value, sensitivity and specificity were 91.7% and 100%, respectively. In addition, when compared with antibody test, concordance rate was 95%. CONCLUSIONS: STANDARDTM E Covi-FERON ELISA showed high sensitivity and specificity, when the cutoff value was 0.24 IU/mL. It was also consistent with the antibody test. IGRA test was a good indicator of cellular immune response in COVID-19 patients.

Evaluation of two SARS-CoV-2 IgG/IgM Rapid Tests in Capillary Blood Samples.

BACKGROUND: As COVID-19 has spread rapidly around the world, it has become essential to detect the virus quickly and accurately for disease prevention and control. Therefore, in response to the COVID-19 pandemic, the need for rapid serological point-of-care test has increased. Recently, many antibody tests have been developed to detect IgM and/or IgG to SARS-CoV-2 in human blood. The authors conducted a prospective study to evaluate the performance of a rapid chromatographic immunoassay and a fluorescent immunoassay for the qualitative detection of specific antibodies, IgM and IgG to SARS-CoV-2 in capillary blood samples, compared to the real-time RT-PCR. METHODS: The subjects included 70 patients who were confirmed positive by real-time RT-PCR and 70 people who were negative. STANDARD Q COVID-19 IgM/IgG Plus Test (chromatographic immunoassay) and Fluorescent immunoassay for IgM and IgG to SARS-CoV-2 (fluorescent immunoassay) were performed using capillary blood samples. Based on the results of real-time RT-PCR assay, clinical sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of two rapid tests were investigated. And the agreement rate between two rapid tests was also presented. RESULTS: Sensitivity, specificity, PPV and NPV of the chromatographic immunoassay were 82.9%, 98.6%, 98.3%, and 85.2%, respectively. At more than 7 days after the onset of symptoms, sensitivity increased to 87.3%. Sensitivity, specificity, PPV, and NPV were 81.4%, 100.0%, 100.0%, and 84.3%, respectively, for the fluorescent immunoassay. At more than 7 days after the onset of symptoms, sensitivity increased to 85.7%. The agreement rate of the two tests was 97.1%. CONCLUSIONS: STANDARD Q COVID-19 IgM/IgG Plus Test and STANDARD F COVID-19 IgM/IgG Combo FIA turned out very specific and sensitive enough to detect individuals infected to SARS-CoV-2. Also, these tests were simple, fast, visually interpretable, and required a small amount of capillary whole blood.

Outbreak of Parainfluenza Virus During the COVID-19 Pandemic at a University Hospital in Korea.

BACKGROUND: The incidence of respiratory viral diseases including parainfluenza virus (PIV) infection has decreased noticeably due to strict quarantine measures during the COVID-19 pandemic. However, the recent outbreak of PIV in children occurred unexpectedly and the distribution pattern showed prominent differences from before the COVID-19 pandemic. PIV is one of the major viral pathogens related to acute lower respiratory infection in young children and the elderly. Accordingly, the authors intended to identify the incidence and distribution pattern of PIV outbreaks and to contribute to public health by providing information on it. METHODS: This study was conducted retrospectively to investigate the incidence and distribution of PIV according to age group, gender, month, and season, and to analyze the co-infections from March 2020 to February 2022. The detection for respiratory microorganisms was performed through FilmArray assay. RESULTS: The overall incidence for at least one respiratory pathogen was 45.9% (665/1,450). PIV was not detected at all from March 2020 to August 2021. However, it was first detected in September 2021 and the rate in the month that followed, October, accounted for 60% (114/190) of the total PIV infections during the entire study period. It also accounted for 44.9% (190/423) of patients with respiratory pathogens from September 2021 to February 2022. It reached the highest proportion at 90.5% (114/126) in October 2021. As for the distribution according to the age groups, group 3 (58.4%) accounted for the highest percentage, followed by group 4 (21.1%). In the PIV positive cases, the overall rate of more than two respiratory pathogens was 32.6% (62/190). The most common pattern of co-infection was PIV3 with rhinovirus/enterovirus (67.7%), followed by PIV3 with adenovirus (8.1%) and PIV3 with rhinovirus/enterovirus and adenovirus (8.1%). CONCLUSIONS: The COVID-19 pandemic has brought about many changes in our daily lives. It has been confirmed that the seasonal distribution of PIV was distinctly different from before the COVID-19 pandemic. It is anticipated that this phenomenon will affect the incidence or distribution of other respiratory pathogens and viral epidemiology. Therefore, clinicians should pay attention to these changes in terms of public health.

Changes in the Distribution of Respiratory Microorganisms before and during the COVID-19 Pandemic, Daegu, Korea.

BACKGROUND: Acute respiratory infection (ARI) is the most common infectious disease in all ages and genders worldwide. Respiratory microorganisms such as respiratory viruses, are commonly responsible for causing ARI. COVID-19 is still prevalent in Korea. The implementation of lockdown and strict control measures, the mandatory wearing of masks, and social distancing are critical steps for controlling the risk of COVID-19 spread. This study was conducted to find out how these changes in daily lives impacted the distribution of respiratory microorganisms. METHODS: A retrospective study was conducted to identify the incidence and distribution patterns of ARI-causing respiratory microorganisms before (Period Ⅰ) and during the COVID-19 pandemic (Period Ⅱ) in terms of detection method, age, month, and season. In particular, data in Periods Ⅰ and Ⅱ were compared for eight major kinds of respiratory microorganisms: adenovirus (AdV), human metapneumovirus (HMPV), human rhinovirus/enterovirus (Rhino/Entero), influenza virus (Flu) A, Flu B, human parainfluenza virus (HPIV) 3, respiratory syncytial virus, and Mycoplasma pneumoniae. RESULTS: A total of 27,191 respiratory specimens were tested, of which 5,513 were obtained from children and adolescents (age groups 1 ⁓ 5) and 21,678 from adults (age group 6). The overall positive rates for at least one respiratory microorganism in Periods Ⅰ and Ⅱ were 23.1% (1,199/5,193) and 4.9% (1,070/21,998), respectively (p < 0.001). The overall positive rates in male and female patients were significantly different (8.7% vs. 7.9%; p = 0.016). On the FilmArray™ RP assay, positive rates in all age groups decreased significantly in Period Ⅱ compared with Period Ⅰ. AdV, Rhino/Entero, and Flu A were detected in all four seasons, but HMPV and HPIV3 were not detected. The overall positive rates on FilmArray and the Flu antigen test in Period Ⅱ were significantly decreased. In the COVID-19 test, the positive rates were high in March and April 2020, and decreased thereafter, but these increased again in the winter of 2020/2021. CONCLUSIONS: Life changes due to COVID-19 pandemic have had a significant impact on the distribution of respiratory microorganisms; our study results might provide useful information on respiratory virus epidemiology.

Severe Acute Respiratory Syndrome Coronavirus-2 Antibody Responses in Hospitalized Patients with Coronavirus Disease 2019 in Daegu, Korea.

BACKGROUND: Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) started to spread in Daegu beginning at the end of February 2020. IgG and IgM antibodies against SARS-CoV-2 were measured in hospitalized patients with COVID-19 with moderate to severe symptoms to improve the understanding of antibody responses. METHODS: We enrolled 312 patients with COVID-19 admitted to seven hospitals located in Daegu. Using serum (or plasma) samples from patients with polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infections, both IgG and IgM antibodies were measured using commercial enzyme-linked immunosorbent assay (R-FIND CO¬VID-19 ELISA, SG medical, Seoul, Korea). RESULTS: The median value from the initial diagnosis, confirmed by SARS-CoV-2 PCR, to the sampling date was 24 days (day 1 to 88). The total positive rate of IgG was 93.9% and the positive IgM rate was 39.4%, without considering the elapsed period after diagnosis. Positive IgG and IgM rates were highest at 100.0% and 59.0%, respectively, at 3 weeks (15 - 21 days). IgG showed a high positive rate of 79.3% even within 7 days after the initial diag-nosis of the disease and maintained a positive rate of 97.8% until after 8 weeks. CONCLUSIONS: Among hospitalized patients with COVID-19, IgG was detected from the beginning of the diagnosis and persisted for an extended time period.

Prevalence of SARS-CoV-2 Antibody in 2,935 Healthcare Workers at 6 Major Hospitals, Daegu, Korea.

BACKGROUND: In Korea, the first community outbreak of coronavirus disease 2019 (COVID-19) occurred in Daegu on February 18, 2020. This study was performed to investigate the prevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibodies in healthcare workers (HCWs) at 6 major hospitals in Daegu. METHODS: Blood specimens of 2,935 HCWs at 6 major hospitals in Daegu from January 2021 to February 2021 were collected. Every specimen was tested for antibody against SARS-CoV-2 using both Elecsys Anti-SARS-CoV-2 electrochemiluminescence immunoassay (Roche Diagnostics, Rotkreuz, Switzerland) and R-FIND COVID-19 IgG/M/A enzyme-linked immunosorbent assay kit (SG medical Inc., Seoul, Korea) as screening tests. If 1 or more of these screening test results was positive, 2 additional antibody tests were performed using Abbott Anti-SARS-CoV-2 IgG assay (Abbott, Abbott Park, IL, USA) and cPass SARS-CoV-2 Neutralization Antibody Detection Kit (GenScript USA Inc., Piscataway, NJ, USA). If 2 or more of the total 4 test results were positive, it was determined as positive for the antibody against SARS-CoV-2. RESULTS: According to the criteria of SARS-CoV-2 antibody positivity determination, 12 subjects were determined as positive. The overall positive rate of the SARS-CoV-2 antibody was 0.41% (12/2,935). Of the 12 subjects determined as positive, 7 were diagnosed with COVID-19, and the remaining 5 were nondiagnosed cases of COVID-19. CONCLUSION: In early 2021, the overall seroprevalence of SARS-CoV-2 antibody among HCW located in Daegu was 0.41%, and 0.17% excluding COVID-19 confirmed subjects. These results were not particularly high compared with the general public and were much lower than HCWs in other countries.

Comprehensive Laboratory Data Analysis to Predict the Clinical Severity of Coronavirus Disease 2019 in 1,952 Patients in Daegu, Korea.

BACKGROUND: Laboratory parameter abnormalities are commonly observed in COVID-19 patients; however, their clinical significance remains controversial. We assessed the prevalence, characteristics, and clinical impact of laboratory parameters in COVID-19 patients hospitalized in Daegu, Korea. METHODS: We investigated the clinical and laboratory parameters of 1,952 COVID-19 patients on admission in nine hospitals in Daegu, Korea. The average patient age was 58.1 years, and 700 (35.9%) patients were men. The patients were classified into mild (N=1,612), moderate (N=294), and severe (N=46) disease groups based on clinical severity scores. We used chi-square test, multiple comparison analysis, and multinomial logistic regression to evaluate the correlation between laboratory parameters and disease severity. RESULTS: Laboratory parameters on admission in the three disease groups were significantly different in terms of hematologic (Hb, Hct, white blood cell count, lymphocyte%, and platelet count), coagulation (prothrombin time and activated partial thromboplastin time), biochemical (albumin, aspartate aminotransferase, alanine aminotransferase, lactate, blood urea nitrogen, creatinine, and electrolytes), inflammatory (C-reactive protein and procalcitonin), cardiac (creatinine kinase MB isoenzyme and troponin I), and molecular virologic (Ct value of SARS-CoV-2 RdRP gene) parameters. Relative lymphopenia, prothrombin time prolongation, and hypoalbuminemia were significant indicators of COVID-19 severity. Patients with both hypoalbuminemia and lymphopenia had a higher risk of severe COVID-19. CONCLUSIONS: Laboratory parameter abnormalities on admission are common, are significantly associated with clinical severity, and can serve as independent predictors of COVID-19 severity. Monitoring the laboratory parameters, including albumin and lymphocyte count, is crucial for timely treatment of COVID-19.

How to keep patients and staff safe from accidental SARS-CoV-2 exposure in the emergency room: Lessons from South Korea's explosive COVID-19 outbreak.

OBJECTIVES: We report our experience with an emergency room (ER) shutdown related to an accidental exposure to a patient with coronavirus disease 2019 (COVID-19) who had not been isolated. SETTING: A 635-bed, tertiary-care hospital in Daegu, South Korea. METHODS: To prevent nosocomial transmission of the disease, we subsequently isolated patients with suspected symptoms, relevant radiographic findings, or epidemiology. Severe acute respiratory coronavirus 2 (SARS-CoV-2) reverse-transcriptase polymerase chain reaction assays (RT-PCR) were performed for most patients requiring hospitalization. A universal mask policy and comprehensive use of personal protective equipment (PPE) were implemented. We analyzed effects of these interventions. RESULTS: From the pre-shutdown period (February 10-25, 2020) to the post-shutdown period (February 28 to March 16, 2020), the mean hourly turnaround time decreased from 23:31 ±6:43 hours to 9:27 ±3:41 hours (P < .001). As a result, the proportion of the patients tested increased from 5.8% (N=1,037) to 64.6% (N=690) (P < .001) and the average number of tests per day increased from 3.8±4.3 to 24.7±5.0 (P < .001). All 23 patients with COVID-19 in the post-shutdown period were isolated in the ER without any problematic accidental exposure or nosocomial transmission. After the shutdown, several metrics increased. The median duration of stay in the ER among hospitalized patients increased from 4:30 hours (interquartile range [IQR], 2:17-9:48) to 14:33 hours (IQR, 6:55-24:50) (P < .001). Rates of intensive care unit admissions increased from 1.4% to 2.9% (P = .023), and mortality increased from 0.9% to 3.0% (P = .001). CONCLUSIONS: Problematic accidental exposure and nosocomial transmission of COVID-19 can be successfully prevented through active isolation and surveillance policies and comprehensive PPE use despite longer ER stays and the presence of more severely ill patients during a severe COVID-19 outbreak.