Lower Ct Values Research Articles

Diagnostic performance of GENEDIA W and ActiveXpress+ COVID-19 antigens tests among symptomatic individuals in Peru and The United Kingdom.

In order to generate independent performance data regarding accuracy of COVID-19 antigen-based rapid diagnostic tests (Ag-RDTs), prospective diagnostic evaluation studies across multiple sites are required to evaluate their performance in different clinical settings. This report describes the clinical evaluation the GENEDIA W COVID-19 Ag Device (Green Cross Medical Science Corp., Chungbuk, Korea) and the ActiveXpress+ COVID-19 Complete Testing Kit (Edinburgh Genetics Ltd, UK), in two testing sites Peru and the United Kingdom. Nasopharyngeal swabs collected from 456 symptomatic patients at primary points of care in Lima, Peru and 610 symptomatic participants at a COVID-19 Drive-Through testing site in Liverpool, England were analyzed by Ag-RDT and compared to RT-PCR. Analytical evaluation of both Ag-RDTs was assessed using serial dilutions of direct culture supernatant of a clinical SARS-CoV-2 isolate from the B.1.1.7 lineage. For GENEDIA brand, the values of overall sensitivity and specificity were 60.4% [95% CI 52.4-67.9%], and 99.2% [95% CI 97.6-99.7%] respectively; and for Active Xpress+ the overall values of sensitivity and specificity were 66.2% [95% CI 54.0-76.5%], and 99.6% [95% CI 97.9-99.9%] respectively. The analytical limit of detection was determined at 5.0 x 102 pfu/ml what equals to approximately 1.0 x 104 gcn/ml for both Ag-RDTs. The UK cohort had lower median Ct values compared to that of Peru during both evaluations. When split by Ct, both Ag-RDTs had optimum sensitivities at Ct<20 (in Peru; 95% [95% CI 76.4-99.1%] and 100.0% [95% CI 74.1-100.0%] and in the UK; 59.2% [95% CI 44.2-73.0%] and 100.0% [95% CI 15.8-100.0%], for the GENDIA and the ActiveXpress+, respectively). Whilst the overall clinical sensitivity of the Genedia did not meet WHO minimum performance requirements for rapid immunoassays in either cohort, the ActiveXpress+ did so for the small UK cohort. This study illustrates comparative performance of Ag-RDTs across two global settings and considers the different approaches in evaluation methods.

A follow up study of cycle threshold values of SARS-CoV-2 in Hunan Province, China.

Since the epidemic of the severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), many governments have used reverse transcription polymerase chain reaction (RT-PCR) to detect the virus. However, there are fewer measures of CT values information based on RT-PCR results, and the relationship between CT values and factors from consecutive tests is not clear enough. So in this study, we analyzed the connection between CT values and the factors based on cohort data from Delta variant of SARS-CoV-2 in Hunan Province. Previous studies have showed that the mean age of the cases was 33.34 years (±18.72 years), with a female predominance (55.03%, n=71), and the greatest proportion of clinical symptoms were of the common type (60.47%, n=78). There were statistical differences between the N and ORF1ab genes in the CT values for the cases. Based on the analysis of the association between CT values and the factors, the lowest CT values were obtained for the unvaccinated, older and clinically symptomatic group at 3-10 days, the maximum peak of viral load occurred. Therefore, it is recommended to use patient information to focus on older, clinically symptomatic, unvaccinated patients and to intervene promptly upon admission.

Effectiveness of Inactivated Vaccine against SARS-CoV-2 Delta Variant Infection in Xiamen, China—A Test-Negative Case-Control Study

Vaccine effectiveness can measure herd immunity, but the effectiveness of inactivated vaccines in Xiamen remains unclear. Our study was designed to understand the herd immunity of the COVID-19 inactivated vaccine against the SARA-CoV-2 Delta variant in the real world of Xiamen. We carried out a test-negative case-control study to explore the vaccine's effectiveness. Participants aged over 12 years were recruited. A logistic regression was used to estimate the odds ratio (OR) of the vaccine among cases and controls. This outbreak began with factory transmission clusters, and spread to families and communities during the incubation period. Sixty percent of cases were confirmed in a quarantine site. A huge mass of confirmed cases (94.49%) was identified within three days, and nearly half of them had a low Ct value. Following an adjustment for age and sex, a single dose of inactivated SARS-CoV-2 vaccine yielded the vaccine effectiveness (VE) of the overall case, of 57.01% (95% CI: -91.44~86.39%), the fully VE was 65.72% (95% CI: -48.69~88.63%) against COVID-19, 59.45% against moderate COVID-19 and 38.48% against severe COVID-19, respectively. The VE of fully vaccinated individuals was significantly higher in females than in males (73.99% vs. 46.26%). The VE among participants aged 19~40 and 41~61 years was 78.75% and 66.33%, respectively, which exceeds the WHO's minimal threshold. Nevertheless, the VE in people under 18 and over 60 years was not observed because of the small sample size. The single-dose vaccine had limited effectiveness in preventing infection of the Delta variant. The two doses of inactivated vaccine could effectively prevent infection, and clinical mild, moderate, and severe illness caused by the SARS-CoV-2 Delta variant in people aged 18-60 years in the real world.

Whole-Genome Analysis of Influenza A(H3N2) and B/Victoria Viruses Detected in Myanmar during the COVID-19 Pandemic in 2021.

An influenza circulation was observed in Myanmar between October and November in 2021. Patients with symptoms of influenza-like illness were screened using rapid diagnostic test (RDT) kits, and 147/414 (35.5%) upper respiratory tract specimens presented positive results. All RDT-positive samples were screened by a commercial multiplex real-time polymerase chain reaction (RT-PCR) assay, and 30 samples positive for influenza A(H3N2) or B underwent further typing/subtyping for cycle threshold (Ct) value determination based on cycling probe RT-PCR. The majority of subtyped samples (n = 13) were influenza A(H3N2), while only three were B/Victoria. Clinical samples with low Ct values obtained by RT-PCR were used for whole-genome sequencing via next-generation sequencing technology. All collected viruses were distinct from the Southern Hemisphere vaccine strains of the corresponding season but matched with vaccines of the following season. Influenza A(H3N2) strains from Myanmar belonged to clade 2a.3 and shared the highest genetic proximity with Bahraini strains. B/Victoria viruses belonged to clade V1A.3a.2 and were genetically similar to Bangladeshi strains. This study highlights the importance of performing influenza virus surveillance with genetic characterization of the influenza virus in Myanmar, to contribute to global influenza surveillance during the COVID-19 pandemic.

Limitation of Interpreting a Single COVID Cycle Threshold Value

Abstract The United States reported its first case of coronavirus disease 2019 (COVID-19) in January 2020. There was limited testing capacity at the time, and the causative agent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was indeed extremely infectious. Testing, therefore, has become a vital part of controlling the COVID-19 pandemic. Nucleic acid amplification tests, such as polymerase chain reaction platform, a value called cycle threshold (Ct) is reported. This number represents the number of polymerase chain reaction test cycles it takes for the sample to become positive. It is inversely proportional to the amount of viral RNA present in the sample. Therefore, a high Ct value infers a low quantity of viral RNA, and conversely, a low Ct value implies high viral RNA, which in turn correlates with infectivity. When interpreted appropriately with the right clinical context, it could be used to assess the infectiousness of an individual. In September 2021, a 73-year-old man who previously completed a primary series of Moderna vaccine (2 injections) presented to the hospital with chest pain. Cardiac catheterization showed multivessel coronary artery disease and was deemed to have unstable angina. The plan was to undergo coronary aortic bypass graft surgery. Preoperative routine testing revealed a positive COVID-19 polymerase chain reaction test with a high Ct value. During the hospital stay, it was shown that he had a decreased Ct value and thus was determined to have an acute case of asymptomatic COVID-19 infection. His surgery was delayed according to the isolation protocol per Centers for Disease Control and Prevention for safety precautions. He eventually underwent coronary aortic bypass graft after completion of isolation and had an uneventful postoperative course. It was also documented that he had serological seroconversion consistent with acute COVID-19 infection. This case illustrates that reporting Ct values is useful in a certain clinical context, but clinicians need to be familiar with the transmissibility and history of SARS-CoV-2 infection as well as understanding the interpretation of positive tests. The appropriate clinical approach and management should be assessed based on exposure history, epidemiology, physical examination, radiographic assessment, and laboratory studies.

Comparison between the accuracy of chest computerized tomography vs. reverse transcriptase polymerase chain reaction in a tertiary care center in Lebanon; along with their correlation to mortality, morbidity and symptoms in COVID-19 patients

ObjectivesChest Computerized Tomography has been widely used in COVID patients' assessment. Hence the question arises as to whether there is any correlation between the Ct value and findings on Chest CT scan or clinical presentation of the patient. We wanted to test the hypothesis of whether low Ct values (≤30) in RT-PCR were associated with a high mortality rate, CT scan findings, or with comorbidities such as immunosuppression and lung disease. MethodsThe radiographic records and RT-PCR Ct values of 371 COVID patents diagnosed at the American University of Beirut Medical Center were reviewed. ResultsWe found out that the sensitivity of chest CT scan compared to RT-PCR, the gold standard, turned out to be 74% (95% CI 69–79%). Specificity, on the other hand was 33% (95% CI 16–55%). The positive predictive value of CT was 94% (95% CI 91–97%) and the negative predictive value was 8% (95% CI 4–16%). low Ct values in RT-PCR were not associated with a higher mortality rate (p-value = 0.416). There was no significant positive association between low Ct value and suspicious CT scan findings (typical and indeterminate for COVID-19), with a p-value of 0.078. There was also no significant association between low Ct value and immunosuppression (p-value = 0.511), or lung disease (p-value =0.06). CT scan findings whether suspicious or not for COVID-19 infection, were not shown to be significantly associated with respiratory symptoms of any kind.No association was found between a history of lung disease, immunosuppression and suspicious CT scan findings for COVID-19. ConclusionAs long as this pandemic exists, nucleic acid testing was and remains the gold standard of COVID-19 diagnosis worldwide and in our community as it has a superior diagnostic accuracy to CT scan and higher sensitivity (94% vs 74%).

Sensitivity and specificity of a rapid antigen assay for the detection of SARS-CoV-2 during the surge of B.1.1.529 variant

Background: As COVID-19 spread across the globe, the new variants continued to emerge, leading to a rapid surge in the cases and thereby overwhelming the testing laboratories. As Rapid antigen test kits became available, they complimented the reverse transcription polymerase chain reaction (RT-PCR) based testing and thereby moderately disburdening the testing laboratories. However, to increase the testing capacities, the regulatory authorities approved these rapid kits with little scrutiny. Therefore, validation of rapid antigen testing kits becomes essential before they are used as viable alternatives to RT-PCR based testing. Aims and Objectives: The aim of this study was to compare the sensitivity and specificity of OSKIT SARS-CoV-2 corona antigen test (Oscar Medicare Pvt. Ltd., India) to that of COVID-19 ONE-STEP RT-PCR KIT (Meril Diagnostics Pvt. Ltd., India). Materials and Methods: In this prospective study, spanning the peak of third wave in India (Between December 1 and January 31, 2022), 242 specimens were collected and analyzed by comparing their results both by OSKIT SARS-CoV-2 Corona Antigen Test and COVID-19 ONE-STEP RT-PCR KIT. The various clinico-epidemiological attributes of the patients were taken into consideration and used to analyze the results. Results: Rapid antigen tests (RAT) was positive in 44 individuals, giving an overall sensitivity of 67.31%. Sensitivity increased when Ct value of below 30 was taken a positive or when only symptomatic individuals were taken for analysis. Sensitivity was highest in case the duration of symptoms was &lt;5 days (92.86%). When comparing RAT results with Ct value of the screening gene (N gene), a higher proportion of positive cases was observed for lower Ct values. Further analysis revealed that majority of the RAT positive cases were from that subset of symptomatic patients who had a history of symptoms of &lt;5 days. Conclusion: The COVID-19 rapid antigen test evaluated in this study was able to detect SARS-CoV-2 infection with high viral loads in both asymptomatic and symptomatic individuals. Thus, this test can serve as a rapid tool for reducing community spread of the virus. The study concludes that the duration since symptom onset greatly affects sensitivity of antigen testing.

Performance Evaluation of Different RT-PCR Kits for the Direct Detection of SARS-CoV-2 in Preheated Specimens.

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has created high demand for molecular kits and consumables for mass screening of suspected individuals. Direct real-time polymerase chain reaction (RT-PCR) assay without nucleic acid extraction has several advantages in saving testing time and cost and helps in the rapid reporting of SARS-CoV-2. The present study evaluated the analytical performance of four SARS-CoV-2 RT-PCR for direct RT-PCR testing using preheated specimens. Methods A total of 100 clinical specimens were selected and divided into three different groups: (1) group I: 20 SARS-CoV-2 positive specimens with high viral load, viz., low Ct values (< 30 Ct), (2) group II: 50 SARS-CoV-2 positive specimens with low viral load, viz., high Ct values (> 30 Ct), and (3) group III: 30 SARS-CoV-2 negative specimens. Specimens were heat-inactivated at 70°C for 10 minutes and cooled down at 4°C and were evaluated for standard and direct RT-PCR method by using ViralDtect-II Multiplex Real-Time PCR kit, TaqPath COVID-19 Combo kit, COVIDsure Pro Multiplex RT-PCR kit, and Hi-PCR Coronavirus (COVID-19) Multiplex Probe PCR kit. Results Results showed that except ViralDtect-II kit, the other three TaqPath COVID-19 Combo kit, COVIDsure Pro kit, and Hi-PCR Coronavirus (COVID-19) RT-PCR kit were able to amplify all the SARS-CoV-2 genes in the direct RT-PCR method using preheated specimens. In group I specimens, 100% sensitivity was observed in all three RT-PCR kits. In group II specimens, COVIDsure Pro kit was found to be superior among other kits. Conclusion Direct RT-PCR method during pandemic situation is valuable and cost effective for the detection of SARS-CoV-2. All three TaqPath COVID-19 Combo kit, COVIDsure Pro kit, and Hi-PCR Coronavirus (COVID-19) RT-PCR kit can be used for direct RT-PCR method and COVIDsure Pro kit performance was found to be superior among all.

Evaluation of the Rapid Antigen Detection Test for Diagnosing SARS-CoV-2 during the COVID-19 Pandemic: Experience from a Centralized Isolation Site in Shanghai, China.

Rapid and reliable diagnosis is important for the management of individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The rapid antigen detection test (RADT) is a rapid, inexpensive, and easy method. Several studies have reported that RADTs performed well in many countries; however, very few studies have been reported in China. In this study, we assessed the performance of the RADT (Ediagnosis COVID-19 antigen test kit). This study was conducted in a centralized isolation site in Shanghai and enrolled 716 patients with COVID-19 and 203 noninfected participants. Nasopharyngeal swabs from all participants were collected on the same day and tested using the RADT and real-time reverse transcription-PCR (RT-PCR). The performance of the RADT was evaluated in different scenarios, such as threshold cycle (CT) values, symptomatic phase, and symptoms on the day of testing. The results demonstrated that the sensitivity for patients with CT values lower than 20 was 96.55% (95% confidence interval [CI], 87.05 to 99.4). The sensitivities were 78.4% (95% CI, 69.96 to 85.05) for participants within 5 days after the first RT-PCR-positive result and 90.77% (95% CI, 80.34 to 96.19) within 5 days after symptom onset. Moreover, the sensitivity of the RADT was more than 80% for patients with symptoms on the day of testing, including fever (89.29%), cough (86.84%), stuffy nose (92.59%), runny nose (92%), sore throat (81.25%), and muscle pain (80.77%), especially for those with upper respiratory tract symptoms. The specificity of the RADT was good in all scenarios. During the SARS-CoV-2 epidemic, Ediagnosis performed excellently in individuals with a higher viral load (evidenced by lower CT values), individuals in the early symptomatic phase, and especially those with upper respiratory tract symptoms. IMPORTANCE RADTs have demonstrated excellent performance in many counties for screening SARS-CoV-2 infection, but very few studies have been conducted in China. The performance of RADTs is largely related to different real-life scenarios. In our study, the performance of the RADT was evaluated in different scenarios, such as CT values, symptomatic phase, and symptoms on the day of testing. The results demonstrated that Ediagnosis (an RADT made in China) performed excellently for individuals with a higher viral load (evidenced by lower CT values), individuals in the early symptomatic phase, and especially those with upper respiratory tract symptoms.

Measles Outbreak Response Activity in Japan, and a Discussion for a Possible Strategy of Outbreak Response Using Cycle Threshold Values of Real-Time Reverse Transcription PCR for Measles Virus in Measles Elimination Settings.

Measles is a highly contagious, but vaccine-preventable disease caused by the measles virus (MeV). Although the administration of two doses of measles vaccines is the most effective strategy to prevent and eliminate measles, MeV continues to spread worldwide, even in 2022. In measles-eliminated countries, preparedness and response to measles outbreaks originating from imported cases are required to maintain elimination status. Under these circumstances, real-time reverse transcription (RT) PCR for MeV could provide a diagnostic method capable of strengthening the subnational capacity for outbreak responses. Real-time RT-PCR can detect MeV RNA from patients with measles at the initial symptomatic stage, which can enable rapid public health responses aimed at detecting their contacts and common sources of infection. Furthermore, low cycle threshold (Ct) values (i.e., high viral load) of throat swabs indicate high infectiousness in patients with measles. The high basic reproduction number of measles suggests that patients with high infectiousness can easily become super-spreaders. This opinion proposes a possible strategy of rapid and intensive responses to counter measles outbreaks caused by super-spreader candidates showing low Ct values in throat swabs. Our strategy would make it possible to effectively prevent further measles transmission, thereby leading to the early termination of measles outbreaks.

Association Between Cycle Threshold Value of Cartridge-Based Nucleic Acid Amplification Test and Clinical Severity of Pulmonary Tuberculosis: A Cross-sectional Study

Introduction: Tuberculosis (TB) is a major global health problem caused by Mycobacterium tuberculosis (MTB). The National Tuberculosis Elimination Programme (NTEP) emphasises early diagnosis and treatment of TB cases. The Cartridge-Based Nucleic Acid Amplification Test (CBNAAT) is a semi-automated molecular assay that rapidly detects MTB Deoxyribonucleic Acid (DNA) and Rifampicin (RIF) resistance-associated mutations using Real-Time Polymerase Chain Reaction (RT-PCR). Aim: This cross-sectional study aims to assess the association between the Cycle Threshold (Ct) value of CBNAAT and the clinical severity of Pulmonary Tuberculosis (PTB). Materials and Methods: The study was conducted at the Department of Respiratory Medicine, Navodaya Medical College Hospital and Research Centre-Raichur, from January 2020 to July 2021. A sample size of 106 participants, aged ≥18 years and meeting the NTEP guidelines for presumptive PTB cases, were enrolled. Participants underwent chest radiography, sputum smear microscopy for Acid-Fast Bacilli (AFB), and CBNAAT testing. Clinical severity of PTB was categorised as mild, moderate, or severe using the Bandim TB score. Data was entered into Microsoft Excel 2017, and statistical analysis was performed using SPSS version 23. Descriptive statistics, frequencies, percentages, means, and standard deviations were calculated, and the chi-square test was utilised to assess associations between qualitative variables. Results: Among the participants, the majority (55.7%, n=59) had moderate clinical severity. Of these, 12.3% (n=13) had high CBNAAT Ct values, 20.8% (n=22) had medium Ct values, 11.3% (n=12) had low Ct values, and 11.3% (n=12) had very low Ct values. A total of 31.1% (n=33) had severe clinical severity, with 13.2% (n=6) having high Ct values, 12.3% (n=13) having medium Ct values, and 6.6% (n=7) each having low and very low Ct values. Additionally, 13.2% (n=14) had mild clinical severity, with 0.9% (n=1) having high Ct values, 3.8% (n=4) having medium Ct values, 5.7% (n=6) having low Ct values, and 2.8% (n=3) having very low Ct values. The chi-square value was 4.697, with a p-value of 0.58. Conclusion: There is no association between the Ct value of CBNAAT and the clinical severity of PTB.

Diagnostic Accuracy of SARS-CoV-2 Rapid Antigen Testing in a Pediatric Population: Children are Not Little Adults.

Information on the use of antigen-based SARS-CoV-2 rapid antigen tests (RAT) in children is limited. RATs have been used more frequently, because they are easily applicable, inexpensive, and can be easily performed at home without the need for special equipment. This study was designed to assign the diagnostic test accuracy of the SARS-CoV-2 RAT in daily clinical practice in children. One thousand forty-two pediatric patients (aged 1 month - 18 years) who presented to the pediatric COVID-19 outpatient clinic of our hospital between January 2021 and June 2022 and met the inclusion criteria were included in this study. Nasopharyngeal samples were taken from the patients at the same visit, first for reverse transcription polymerase chain reaction (RT-PCR) and then for RAT. The data of all patients with RT-PCR positivity (n = 314) and additionally 14 patients with RAT positivity were analyzed in depth. The overall sensitivity and specificity were 62.1% (95% CI: 56.4 - 67.4) and 98% (95% CI: 96.7 - 98.9), respectively. The positive predictive value (PPV) and the negative predictive value (NPV) in this pediatric study were 93.3% and 85.7% (95% CI: 88.7 - 96.1 and 83.1 - 87.9), respectively. Considering the Ct values, which are indirect indicators of viral load, it was observed that the sensitivity of the rapid antigen test increased at low Ct values. The sensitivity increased to 75.1% (95% CI: 67.9 - 81.1) in patients with a Ct value of < 25. The specificity was 92.7% (95% CI: 90.7 - 94.3), PPV was 67.8% (95% CI: 60.7 - 67.8) and the NPV was 94.7% (95% CI: 93.0 - 96.1) in patients with a Ct value < 25. When the patients were evaluated according to their symptomatic/asymptomatic status, the difference between the diagnostic performance of the RAT test was found to be statistically significant (p = 0.006). In our study, it was found that the sensitivity of RATs in pediatric patients was lower than in adults. Our results also showed that children are not small adults, and the sensitivity of the test was higher, especially in symptomatic patients and patients with high viral load. To obtain more accurate results, we believe that performing the test in the first 3 days of symptoms will give more accurate results.

Saliva as a Viable and Simple Alternative to Nasopharyngeal and Oropharyngeal Swabs for COVID-19 Real-Time Reverse Transcriptase Polymerase Chain Reaction

Introduction: Attributable to the difficulties in specimen collection, discomfort and symptoms caused on by Nasopharyngeal (NPS) and Oropharyngeal Swab (OPS) collection, and significant risk to Healthcare Workers (HCW), evaluation of an alternative specimen for the diagnosis of Coronavirus Disease 2019 (COVID-19) is required. Saliva specimen could be an alternative specimen with many advantages over NPS and OPS, however little is known about how well it performs this purpose. Aim: The present study was conducted to assess the efficacy of saliva as a viable and simple alternative specimen to NPS and OPS for COVID-19 Real-Time reverse transcriptase Polymerase Chain Reaction (rRT-PCR). Materials and Methods: The present cross-sectional study was conducted in the Department of Microbiology, SGT Medical College Hospital and Research Institute, Haryana, India, from July 2020 to December 2020. A total of 60 symptomatic and 20 asymptomatic COVID-19 patients were recruited for the study and specimen viz., saliva, NPS and OPS were collected at four different sampling points i.e., on day 1, 5, 7 and 14 after confirmation of COVID-19 rRT-PCR test positivity. Data obtained from the study was analysed and expressed as median, frequency, interquartile range and Chi-square test was done for comparison of categorical variables. Results: Majority of the patients in symptomatic hospitalised COVID-19 patients were males (n=49, 81.7%) and remaining were females (n=11, 18.3%) and in asymptomatic group 8 (40%) were males and 12 (60%) were females. Saliva was the most sensitive specimen (74.2%), followed by NPS, Naso Oropharyngeal Swab (NOPS) with 70.8% each and OPS (65.8%) for detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in symptomatic patients at four different sampling points. Comparable findings were also observed in specimens obtained from asymptomatic individuals as well. In addition, the viral load was also highest in saliva sample, as measured by Cycle Threshold (CT)-value. Across all specimen types, high viral load (lower CT-values) was observed during the early period of infection. Majority of the study participants reported discomfort during NPS and OPS collection (90% and 85%, respectively), lacrimation, sneezing and gag reflex being the most commonly reported induced symptoms. Conclusion: In the present study, saliva could be a viable and alternate specimen for COVID-19 diagnosis due to its ease in sample collection, specimen stability and reduced risk of transmission of infection due to droplets.

Differentiation of Small Gastrointestinal Stromal Tumor and Gastric Leiomyoma with Contrast-Enhanced CT.

The value of multiphase contrast-enhanced CT in differentiating gastrointestinal stromal tumors (GISTs) and gastric leiomyomas (GLMs) which were ≤3 cm was evaluated using machine learning. A retrospective analysis was conducted on 45 cases of small gastric wall submucosal tumors (including 22 GISTs and 23 GLMs) with pathologically confirmed diameter ≤3 cm and completed multiphase CT-enhanced scan images. The CT features including tumor location, maximum diameter, shape, margins, growth pattern, plain/enhanced CT value, cystic degeneration, calcification, ulcer, progressive reinforcement, perilesional lymph nodes, and the CT value ratio of the tumor to the aorta at the same level in the enhanced phase III scan of the two groups were evaluated. Tumor location and maximum diameter were automatically evaluated by machine learning. The GISTs and GLMs with a diameter ≤3 cm showed clear margins, uniform density on plain scan CT, and progressive homogeneous enhancement. The age of the GISTs is greater than that of the GLMs group. The plain scan CT value of the GISTs group was lower than that in the GLMs group. In the GISTs group, the lesions were mostly located in the fundus (68.18%), showing a mixed growth pattern (54.55%), and in the GLMs group, most lesions were located in the cardia (47.82%), showing an intraluminal growth pattern (95.65%). The abovementioned differences were statistically significant. Contrast-enhanced CT has limited value in differentiating small GISTs from GLMs, which are ≤3 cm. Older age (>49.0 years), a low plain CT value (<42.5 Hu), mixed growth inside and outside the cavity, and noncardiac location tended to be the criteria for the diagnosis of small GISTs of the gastric wall.

Associations of SARS-CoV-2 cycle threshold values with age, gender, sample collection setting, and pandemic period.

Cycle threshold (Ct) values in COVID-19 reverse-transcription polymerase chain reaction (RT-PCR) tests estimate the viral load in biological samples. Studies have investigated variables associated with SARS-CoV-2 viral load, aiming to identify factors associated with higher transmissibility. Using the results from tests performed between May/2020-July/2022 obtained from the database of a referent hospital in Sao Paulo, Brazil, we investigated associations between Ct values and patient's age, gender, sample collection setting and pandemic period according to the predominant SARS-CoV-2 variant locally. We also examined variations in Ct values, COVID-19 incidence, mortality, and vaccination coverage over time. The study sample included 42,741 tests. Gender was not significantly associated with Ct values. Age, sample collection setting and the pandemic period were significantly associated with Ct values even after adjustment to the multivariable model. Results showed lower Ct values in older groups, during the Gamma and Delta periods, and in samples collected in emergency units; and higher Ct values in children under 10 years old, home-based tests, during the Omicron period. We found evidence of a linear trend in the association between age and Ct values, with Ct values decreasing as age increases. We found no clear temporal associations between Ct values and local indicators of COVID-19 incidence, mortality, or vaccination between February/2020-November/2022. Our findings suggest that SARS-CoV-2 Ct values, a proxy for viral load and transmissibility, can be influenced by demographic and epidemiological variables.

Evaluation of Liver Function Tests (LFT) and C-reactive protein in COVID-19 (SARS Cov-2) positive patients diagnosed by Real-time PCR

Background/Aim: Unpredicted social and economic consequences have resulted from the SARS-CoV-2 pandemic worldwide. Limited information is currently available addressing the COVID-19 infection impact on the RT-PCR Cycle threshold value trend, infection risk factors, impact on liver enzymes, etc. Methods: From November 2020 to March 2021, a cross-sectional study was carried out in the Chemical Pathology also Molecular Biology divisions of the Pathology Department of Shalamar Hospital, Lahore. Results: Males had a higher risk of contracting SARS-CoV-2 infection than females about 51%. 36.5 percent of total infected people fell within the 20–40 age range. Significant factors that affect the severity of COVID-19 include age and underlying comorbidities. The majority of the patients (78.3%) reported fever, 50.4% had a cough, and 50.1% had myalgias. Low Ct value of RT-PCR may be asignificant predictor of illness severity and risk of mortality, with p values of 0.001 and 0.003, correspondingly. Disease severity was substantially associated with CRP, AST, ALT, and bilirubin indirect. It was observed that the Deritis ratio and CRP were highly associated with the risk of mortality. These markers can therefore be used to evaluate a patient's status as it progresses toward a severe disease, liver damage from treatment, and death risk. Conclusions: For doctors making patient management decisions, real-time PCR data and Ct values for SARS-CoV-2 may be useful. Age and comorbidities, among other risk variables, have been recognized as being associated with the likelihood of having a fatal illness. ALT, AST, Deritis ratio, and CRP are biochemical laboratory indicators that can be considered prognostic biomarkers for the development of severe disease and risk of mortality. Keywords: SARS-CoV-2, COVID-19, Liver, Cough, Pandemic

Multiple-probe-assisted DNA capture and amplification for high-throughput African swine fever virus detection.

African swine fever (ASF) is one of the most devastating infectious diseases affecting domestic pigs and wild boar. The grave socio-economic impact of African swine fever infection at a global level makes large-scale rapid and robust diagnosis a critical step towards effective control. Here, we describe multiple-probe-assisted DNA capture and amplification technology (MADCAT) - a novel, sensitive, simple, and high-throughput method for detecting ASFV directly from whole blood or other complex matrices. Through a unique DNA capture approach which specifically captures the target DNA onto 96-well plate for subsequent amplification, MADCAT abandons the complicated extraction protocol and achieves ultrafast and high-throughput detection. The sample-to-result time for 96 samples is about 90min, as compared with the 3-4h time of the conventional real-time qPCR method. The limit of detection (LOD) of MADCAT is 0.5 copies/μL blood and is 5 times more sensitive than an extraction-based qPCR assay when testing serially diluted whole blood samples. The assay is 100% specific against other common swine pathogens. In the clinical diagnosis of 96 field samples, all 22 positive samples were correctly identified with lower Ct values than extraction-based qPCR, confirming its high diagnostic sensitivity (100%). Owing to its high-throughput, specific high sensitivity, and direct detection features, MADCAT shows great potential for use in large-scale ASFV surveillance and monitoring for effective disease control. KEY POINTS: • No nucleic acid extraction, 100% capture efficiency, and high-throughput • Ultra-high sensitivity of 0.5 DNA copies/μL or 6 DNA copies/reaction • The sample-to-answer time for 96 samples is about 90min.

Impact of TRIM5α and TRIM22 Genes Expression on the Clinical Course of Coronavirus Disease 2019

The innate immune response in humans involves a wide variety of factors, including the tripartite motif-containing 5α (TRIM5α) and 22 (TRIM22) as a cluster of genes on chromosome 11 that have exhibited antiviral activity in several viral infections. We analyzed the correlation of the expression of TRIM5α and TRIM22 with the severity of Coronavirus Disease 2019 (COVID-19) in blood samples of 330 patients, divided into two groups of severe and mild disease, versus the healthy individuals who never had contact with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The transcription level of TRIM5α and TRIM22 was determined by quantitative real-time polymerase chain reaction (qPCR). The laboratory values were collected from the patients' records. The expression of both genes was significantly lower in the severe group containing the hospitalized patients than in both the mild group and the control group. However, in the mild group, TRIM22 expression was significantly higher (p <0.0001) than in the control group while TRIM5α expression was not significantly different between these two groups. We found a relationship between the cycle threshold (Ct) value of patients and the expression of the aforementioned genes. The results of our study indicated that lower Ct values or higher RNA viral load might be associated with the downregulation of TRIM5α and TRIM22 and the severity of COVID-19. Additional studies are needed to confirm the results of this study.

Association of epidemiological and clinical features with PCR cycle threshold values of SARS-CoV-2 infection: a cross-sectional study

ABSTRACT The cycle threshold (Ct) in quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR) is inversely correlated to the amount of viral nucleic acid or viral load and can be regarded as an indicator of infectivity. We examined the association of socio-demographic and clinical characteristics of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) polymerase chain reaction (PCR) positive cases with PCR cycle threshold (Ct) values at the time of diagnosis. SARS-CoV-2 cases reported between 12 October 2020 and 24 January 2021 in Regensburg were analyzed employing bivariate and multivariable methods. We included 3,029 SARS-CoV-2 cases (31% asymptomatic at diagnosis) and analyzed the association of case characteristics with Ct values in 2,606 cases. Among symptomatic patients, cough (38.0%), rhinitis (32.4%), headache (32.0), and fever/chills (29.9%) were the most frequent complaints. Ct values ≤20 were more frequent in symptomatic cases (20.9% vs. 11.3%), whereas Ct values >30 were more common in asymptomatic cases (32.6% vs. 18.0%). Ct values >20 and ≤30 were most common in symptomatic and asymptomatic cases (48.0% vs 40.7%). We observed lower median Ct values of E and N gene in symptomatic cases. In a random forest model, the total number of symptoms, respiratory symptoms, and age were most strongly associated with low Ct values. In conclusion, certain symptoms and age were associated with lower Ct values. Ct values can be used as a pragmatic approach in estimating infectivity at the first notification of a case and, thus, in guiding containment measures.

Evaluation of STANDARDTM M10 SARS-CoV-2 assay as a diagnostic tool for SARS-CoV-2 in nasopharyngeal or oropharyngeal swab samples

The SARS-CoV-2 pandemic led to an urgent need for rapid diagnostic testing in order to inform timely patients’ management. This study aimed to assess the performance of the STANDARD™ M10 SARS-CoV-2 assay as a diagnostic tool for COVID-19. A total of 400 nasopharyngeal or oropharyngeal swabs were tested against a reference real-time RT-PCR, including 200 positive samples spanning the full range of observed Ct values. The sensitivity of the STANDARD™ M10 SARS-CoV-2 assay was 98.00% (95% CI 94.96% to 99.45%, 196/200), while the specificity was also estimated at 97.50% (95% CI 94.26% to 99.18%, 195/200). The assay proved highly efficient for the detection of SARS-CoV-2, even in samples with low viral load (Ct>25), presenting lower Ct values compared to the reference method. We concluded that the STANDARD™ M10 SARS-CoV-2 assay has a similar performance compared to the reference method and other molecular point-of-care assays and can be a valuable tool for rapid and accurate diagnosis.