Association between real-time polymerase chain reaction cycle threshold value and clinical presentation in children with Bordetella pertussis.

BACKGROUND: The cycle threshold (Ct) value is inversely proportional to the number of copies of the target region in a sample, suggesting that a low Ct value indicates a high pathogen load. The relationship between Ct value and clinical presentation in children with pertussis is not well-defined. METHODS: We investigated the relationships between the Ct value of nasopharyngeal samples positive for Bordetella pertussis deoxyribonucleic acid via real-time polymerase chain reaction (PCR), collected from children on admission and their adult family members between May 2022 and March 2024 at Hangzhou Children's Hospital, China. The study focused on the correlation between Ct value and clinical presentation in children with pertussis. RESULTS: The Ct value was positively correlated with age (r = 0.362, P = 0.001). The mean Ct value for children with pertussis was 28.0 (range: 22.0-32.0), which was lower than the 32.0 (range: 30.0-34.0) observed in adults. Ct value was inversely correlated with length of stay, an indicator of disease severity (r = -0.356, P = 0.001). Logistic regression analyses revealed that both Ct value (OR: 0.891, 95% CI: 0.799-0.993, P = 0.036) and white blood cell count (OR: 1.127, 95% CI: 1.005-1.263, P = 0.040) were independently associated with severity of pertussis. CONCLUSIONS: Real-time PCR Ct values at initial diagnosis for pertussis may potentially predict severe disease outcomes in children.

The Impact of Viral Load on the Severity and Outcome Among Patients With COVID-19: A Cross-Sectional Study.

Objectives This study aimed to assess the relationship between illness severity and mortality among COVID-19 patients along with the cycle threshold (Ct) value measured by viral load. Methods A cross-sectional study was conducted based on records of the emergency room at Rashid Hospital located in Dubai, United Arab Emirates. This research was carried out on all of the appropriate records of patients who were hospitalized at Rashid Hospital in Dubai between May 2020 and January 2021. Clinical and laboratory data were used as severity indicators, and in-hospital death was designated as the outcome. Results A total of 1,633 cases were included in the analysis. The percentage of deceased patients was higher in patients with a low Ct value (11.6%) than in patients with a high Ct value (6.9%) (p-value = 0.003). Logistic analysis revealed a statistically significant correlation (OR=2.046; p-value=0.002) between mortality and viral load, as measured by the Ct value. Patients with low Ct values and aberrant laboratory findings had a higher frequency of respiratory problems and required oxygen therapy, according to clinical and laboratory markers. Conclusions A correlation was found between viral load and mortality. Advanced age, history of chronic disease, and abnormal clinical and laboratory findings were all independently linked to a greater mortality rate in COVID-19 patients, indicating that they might be utilized as predictive and prognostic factors along with the viral load.

Long-term trends in cycle threshold values: a comprehensive analysis of COVID-19 dynamics, viral load, and reproduction number in South Korea.

Background: With the emergence of COVID-19 cases, governments quickly responded with aggressive testing, contact tracing, isolation and quarantine measures. South Korea's testing strategy primarily relied on real-time reverse-transcriptase polymerase chain reaction (real-time RT-PCR), focusing on cycle threshold (Ct) values, indicative of viral load, to determine COVID-19 positivity. This study examined the long-term time series distribution of Ct values measured in the same laboratory using a nationally standardized testing type and sampling method in South Korea. It aimed to link Ct values, new COVID-19 cases, and the reproduction number (Rt), setting the stage for using Ct values effectively. Methods: This study analyzed nationally collected 296,347 samples Ct values from February 2020 to January 2022 and examined their associations with the number of new cases and Rt trends. The data were categorized into four COVID-19 periods for in-depth analysis. Statistical methods included time series trend analysis, local regression for smoothing, linear regression for association analysis, and calculation of correlation coefficients. Results: The median Ct values across four COVID-19 periods decreased gradually from 31.71 in the initial period to 21.27 in the fourth period, indicating higher viral load. The comparison of trends between Ct values and the number of new cases revealed that the decline in Ct values preceded the surge in new cases, particularly evident during the initial stages when new cases did not undergo a significant increase. Also, during variant emergence and vaccination rollout, marked shifts in Ct values were observed. Results from linear regression analysis revealed a significant negative relationship between Ct values and new cases (ß = -0.33, p < 0.001, R 2 = 0.67). This implies that as Ct values decrease, new case numbers increase. Conclusion: This study demonstrates the potential of Ct values as early indicators for predicting confirmed COVID-19 cases during the initial stages of the epidemic and suggests their relevance in large-scale epidemic monitoring, even when case numbers are similar.

SARS-CoV-2 Polymerase Chain Reaction Cycle Threshold Trends in Patients Who Are Immunocompromised and Implications for Isolation Precautions.

Among 495 patients who were immunocompromised and tested positive for SARS-CoV-2, polymerase chain reaction cycle thresholds remained <33 beyond 20 days more frequently in patients with hematologic malignancies, particularly those receiving B-cell-depleting or Bruton tyrosine kinase inhibitor therapy, as compared with those with solid organ malignancy (26% vs 5%).

A new antigen test device for rapid influenza A and B detection.

Introduction: Tests for detection of influenza must demonstrate high sensitivity and specificity, affordability, and rapidness. Methods: This study aimed to evaluate the performance of the LabOn-Time™ Influenza A + B Rapid test device (BMT Diagnostics, Ltd), as compared to Real-time polymerase chain reaction (RT-PCR), in identifying influenza A/B among 183 nasopharyngeal samples collected between February and April 2023 from patients with Influenza-like symptoms. Results: Out of 70 participants with a positive RT-PCR result, 53 (75.7 %) had a positive LabOn-Time result. The LabOn-Time kit had a sensitivity of 75.7 % and specificity of 100 %. The odds ratio for showing a false negative LabOn-Time result for influenza B, compared to influenza A was 5.24 (95%CI: 1.35-20.31). All false negative LabOn-Time samples had a RT-PCT cycle threshold ≥20. Mean time from symptom onset was significantly lower in the false negative LabOn-Time cases compared to the positive cases (36 ± 15.3 vs. 42.6 ± 10.1, respectively). The mean number of symptoms reported per patient was significantly higher in positive compared to negative LabOn-Time cases (2.5 ± 0.5 vs. 1.9 ± 0.4, p < 0.001). Conclusions: The LabOn-Time device, which is very simple and intuitive to operate, could significantly contribute to early detection of influenza A/B infection.

Relationship between acute SARS-CoV-2 viral clearance with Long COVID Symptoms: a cohort study.

Introduction: The relationship between SARS-CoV-2 viral dynamics during acute infection and the development of long COVID is largely unknown. Methods: A total of 7361 asymptomatic community-dwelling people enrolled in the Test Us at Home parent study between October 2021 and February 2022. Participants self-collected anterior nasal swabs for SARS-CoV-2 RT-PCR testing every 24-48 hours for 10-14 days, regardless of symptom or infection status. Participants who had no history of COVID-19 at enrollment and who were subsequently found to have ≥1 positive SARS-CoV-2 RT-PCR test during the parent study were recontacted in August 2023 and asked whether they had experienced long COVID, defined as the development of new symptoms lasting 3 months or longer following SARS-CoV-2 infection. Participant's cycle threshold values were converted into viral loads, and slopes of viral clearance were modeled using post-nadir viral loads. Using a log binomial model with the modeled slopes as the exposure, we calculated the relative risk of subsequently developing long COVID with 1-2 symptoms, 3-4 symptoms, or 5+ symptoms, adjusting for age, number of symptoms, and SARS-CoV-2 variant. Adjusted relative risk (aRR) of individual long COVID symptoms based on viral clearance was also calculated. Results: 172 participants were eligible for analyses, and 59 (34.3%) reported experiencing long COVID. The risk of long COVID with 3-4 symptoms and 5+ symptoms increased by 2.44 times (aRR: 2.44; 95% CI: 0.88-6.82) and 4.97 times (aRR: 4.97; 95% CI: 1.90-13.0) per viral load slope-unit increase, respectively. Participants who developed long COVID had significantly longer times from peak viral load to viral clearance during acute disease than those who never developed long COVID (8.65 [95% CI: 8.28-9.01] vs. 10.0 [95% CI: 9.25-10.8]). The slope of viral clearance was significantly positively associated with long COVID symptoms of fatigue (aRR: 2.86; 95% CI: 1.22-6.69), brain fog (aRR: 4.94; 95% CI: 2.21-11.0), shortness of breath (aRR: 5.05; 95% CI: 1.24-20.6), and gastrointestinal symptoms (aRR: 5.46; 95% CI: 1.54-19.3). Discussion: We observed that longer time from peak viral load to viral RNA clearance during acute COVID-19 was associated with an increased risk of developing long COVID. Further, slower clearance rates were associated with greater number of symptoms of long COVID. These findings suggest that early viral-host dynamics are mechanistically important in the subsequent development of long COVID.

A closer look at the link between cycle threshold, clinical features and biomarkers: An observational study in COVID-19 patients.

Background: Symptoms for severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) appear 2-3 days after exposure to the virus. Being a virus, detection is primarily by polymerase chain reaction as this offers superior sensitivity and specificity. There was a misconception that patients with low cycle threshold (Ct) have severe coronavirus disease (COVID), and for individuals with higher Ct, it is the other way around. The prognosis for COVID was derived from various biomarkers and physicians heavily relied on them. Materials and Methods: A cross-sectional study spanning a duration of 2 years was conducted at a tertiary care centre in western India. A total of 201 individuals were included and the correlation between Ct, clinical features and biomarkers was studied. Results: In the E-gene, 43.28% had lower Ct values and 40.79% had low Ct values in the RdRp gene. 50% of all patients had diabetes, with 60% being between the ages of 61 and 80. 54.1% of hypertension patients belonged to ages between 61 and 80. 90.54% of COVID-positive individuals had lactose dehydrogenase levels ranging from 440 to 760. 79% of patients had a procalcitonin value of more than one but less than six. 79.1% of patients had an erythrocyte sedimentation rate between 36 and 90. Conclusion: Ct value though has a research value; it is a poor prognostic marker when compared to the various biomarkers that have been studied earlier. We cannot conclusively state that all our findings are accurate due to a lack of data but further research into the prognostic value of Ct should be conducted which will help in the ongoing scenario.

Correlation of serum Adenosine Deaminase levels with microbiological parameters in Pulmonary Tuberculosis.

Accurate diagnosis of pulmonary tuberculosis is largely based on sputum smear microscopy, culture, and GeneXpert MTB/RIF tests; culture being the gold standard. All these diagnostic tests require sputum sample to be positive for Mycobacterium tuberculosis, while many active TB patients often do not present with M. tuberculosis positive sputum. Biochemical markers play an important role in early diagnosis, disease prevention, and drug response in tuberculosis. This study aims to find the association of serum adenosine deaminase (a biomarker) with the various microbiological parameters like sputum smear microscopy, culture and CBNAAT in pulmonary tuberculosis patients. A total of 40 cases were collected from November 2019 to October 2021, and the presumptive cases of pulmonary tuberculosis diagnosed by Ziehl-Neelsen staining for acid fast bacilli and/or CBNAAT were recruited. Serum adenosine deaminase levels were estimated.The following variables were significantly associated (p < 0.05) with serum adenosine deaminase levels: age, sputum smear microscopy findings, time to culture positivity, CBNAAT category and Ct value (Mean).This study does witness few significant correlations between serum adenosine deaminase levels and various microbiological parameters used in diagnosis of TB, which can be further explored and utilised in diagnosis and treatment of pulmonary tuberculosis.

Use of PCR Cycle Threshold and Clinical Interventions to Aid in the Management of Pediatric Clostridioides difficile Patients.

Better diagnostic tools are needed to improve the diagnosis of Clostridioides difficile infections (CDI) and reduce the overtreatment of colonized children. In this study, we evaluated two polymerase chain reaction (PCR) assays (Cepheid GeneXpert C. difficile and the Gastroenteritis PCR Panel by QIAstat-Dx) as a standalone method in combination with the PCR cycle threshold (Ct) value in positive samples to predict the presence of free toxins. We also evaluated the clinical impact of reporting toxin production results and provided comments alongside the PCR results in our pediatric population. PCR-positive stool samples from pediatric patients (aged 2 to 18 years old) were included in our study and tested for the presence of toxins A and B using the C. difficile Quik Chek Complete kit. For the clinical intervention, the CDI treatment rates 6 months pre- and post-intervention were compared. The use of PCR Ct value showed excellent sensitivity (100%) at a Ct value cutoff of 26.1 and 27.2 using the Cepheid GeneXpert C. difficile and the Gastroenteritis PCR Panel by QIAstat-Dx, respectively, while the toxin test showed inferior sensitivity of 64% in the PCR-positive samples. In addition, CDI treatment rates were decreased by 23% post-intervention. The results of our study suggest that nucleic acid amplification test (NAAT) assays supplemented by the use of PCR Ct value for positive samples can be used as standalone tests to differentiate CDI from colonization. Furthermore, the reporting of toxin production along with the PCR results can help reduce the unnecessary treatment of colonized children.

Pathogenic Role of Human Rhinovirus Mono-Infection in Pediatric Lower Respiratory Tract Infection.

Background and objective Human rhinovirus (HRV) is one of the leading causes of pediatric respiratory tract infection with a prevalence rate of 30-50%, mostly affecting children below five years of age and causing a substantial amount of economic loss. In children, it can alone or as a co-infection, cause a wide range of symptoms from mild to life-threatening ones. With the above background, the current study was carried out to emphasize the role of HRV mono-infection in pediatric acute respiratory tract infections by correlating clinical and molecular laboratory findings. Methods This study was carried out in a tertiary care teaching hospital over a duration of four years (March 2019-October 2023). Children up to 14 years of age visiting the outpatient department or admitted to the ward with diagnoses of acute respiratory tract infections (ARTIs) were included. The clinical and laboratory data were retrieved and analyzed. A nasopharyngeal swab (NPS) or throat swab (TS) was collected and sent to the Microbiology laboratory maintaining the cold chain. Nucleic acid was extracted and subjected to multiplex real-time polymerase chain reaction (RT-PCR). Result Of the 245 samples tested for the respiratory viral pathogen, 52 samples tested positive for HRV, of which 27 had HRV mono-infection. The clinico-demographic details of these 27 patients were studied in detail. The majority of the cases (24/27; 88.8%) were less than five years of age. Fever and shortness of breath were the most consistent symptoms in all. Nineteen (19/27; 62.9%) HRV mono-infection cases had underlying co-morbidities, all requiring respiratory support. The HRV mono-infection cases either developed bronchiolitis, lower respiratory tract infection, or pneumonia. All mono-infection cases had cycle threshold value (Ct) < 25, while the Ct value of HRV was > 30 in co-infection with other viruses. Conclusion Mono-infection of HRV in under-five children with underlying comorbidities and a lesser Ct value indicates severe disease manifestation and should be dealt with more cautiously.

Comparative evaluation of the STANDARD M10 and Xpert C. difficile assays for detection of toxigenic Clostridioides difficile in stool specimens.

This study compared the performance of two commercial molecular assays, the STANDARD M10 Clostridioides difficile assay (M10) and the Xpert C. difficile assay (Xpert), for detecting toxigenic C. difficile in stool specimens. A total of 487 consecutive stool specimens submitted for routine C. difficile testing between June and November 2023 were included. Following routine testing using C. DIFF QUIK CHEK COMPLETE (QCC), M10 and Xpert were tested in parallel, alongside toxigenic culture (reference standard). Additionally, two-step algorithms, using QCC on the first step and either M10 or Xpert on the second step, were assessed. Both M10 and Xpert demonstrated a sensitivity and negative predictive value (NPV) of 100%. M10 exhibited significantly higher specificity and positive predictive value (PPV; 91.9% and 64.2%, respectively) than Xpert (90.3% and 59.8%, respectively). Both two-step algorithms showed a sensitivity and NPV of 98.4% and 99.8%, respectively. The specificity and PPV of the two-step algorithm using M10 (95.2% and 75.0%, respectively) were slightly higher than those of the one using Xpert (94.8% and 73.2%, respectively), without statistical significance. Receiver operating characteristic curve analysis, assessing the predictive ability of cycle threshold (Ct) values for the detection of free toxin, exhibited an area under the curve of 0.825 for M10 and 0.843 for Xpert. This indicates the utility of Ct values as predictors for the detection of free toxin in both assays. In conclusion, M10 proves to be an effective diagnostic tool with performance comparable to Xpert, whether utilized independently or as part of a two-step algorithm.

Transitioning from Triton X-100 to Tergitol 15-S-9: impacts on diagnostic assays using viral PCR sample solution.

In 2019, the European Union banned Triton X-100, a detergent widely used in laboratory diagnostics, including the Viral PCR Sample Solution (VPSS), and urged manufacturers to find environmentally sustainable alternatives. Tergitol 15-S-9 (VPSS2) has been proposed as an alternative surfactant. This multicenter study evaluated the effectiveness of VPSS2, a Tergitol-based viral solution, as a replacement for VPSS. Our results show the equivalent performance of VPSS2 to VPSS for nucleic acid extraction and viral stability over time at different temperatures. The new VPSS formulation was also tested against external quality assurance panels and clinical samples. The results of this work support adopting this modified viral PCR sample solution to replace Triton X-100-containing viral transport solutions.

The European Union has banned Triton X-100. All reagents containing it should be replaced. Could a new Viral PCR Sample Solution (VPSS) containing Tergitol 15-S-9 be a suitable replacement?

Correlation between the Cycle Threshold Values in Detection of Severe Fever with Thrombocytopenia Syndrome Virus Using PowerChekTM SFTSV Real-Time PCR Kit and Viral Load: Prognostic Implications.

BACKGROUND: This study aimed to analyze the correlation between the cycle threshold (Ct) values of severe fever with thrombocytopenia syndrome (SFTS) virus small (S) and middle (M) segments and the SFTS viral load, aiming to estimate the initial viral load and predict prognosis in the early clinical course. METHOD: A retrospective study was conducted with confirmed SFTS patients at Jeju National University Hospital (2016-2022). Patients were categorized into non-fatal and fatal groups. RESULTS: This study included 49 patients with confirmed SFTS (non-fatal group, n = 42; fatal group, n = 7). A significant negative correlation (-0.783) was observed between the log SFTS viral load and Ct values (p < 0.001). This negative correlation was notably stronger in the fatal group (correlation coefficient -0.940) than in the non-fatal group (correlation coefficient -0.345). CONCLUSION: In this study, we established a correlation between SFTS viral load and Ct values for estimating the initial viral load and early predicting prognosis. These results are expected to offer valuable insights for SFTS patient treatment and prognosis prediction.

Kinetics of SARS-CoV-2 Viral Load in Hospitalized Patients.

The rapid and accurate detection of infectious people is crucial in controlling outbreaks. The aim of this study was to evaluate the kinetics of the viral load expressed as Ct in COVID-19 hospitalized patients. Nasopharyngeal swab specimens were collected for RT-PCR testing. Forty-one subjects were recruited, of which 48.8% developed severe symptoms and 51.2% showed milder symptoms. The distribution of Ct values measured from the symptom onset showed that the kinetics of the viral load decreased with increasing time. A Ct of 25 (high viral load) was reached after a mean of 9.9 ± 4.8 days from the symptom onset, without a significant difference between patients with severe (10.9 ± 5.7 days) and milder (9.0 ± 3.9 days) symptoms. In 65.8% of cases, a high viral load was maintained for more than 7 days from the symptom onset, especially in patients with severe symptoms (70.6%). A Ct of 30 (moderate viral load) and of 38 (low viral load) were reached after a mean of 16.1 ± 8.1 and 28.5 ± 22.4 days from the symptom onset, respectively, with a significant difference between patients with severe (Ct = 30:17.9 ± 9.8 days; Ct = 38:34.6 ± 29.6 days) and milder (Ct = 30:14.3 ± 5.8 days; Ct = 38:22.7 ± 9.9 days) symptoms. These results provide an understanding of the viral kinetics of SARS-CoV-2 and have implications for pandemic control strategies and practices.

Saliva as a Biological Fluid in SARS-CoV-2 Detection.

BACKGROUND: The polymerase chain reaction of upper respiratory tract swab samples was established as the gold standard procedure for diagnosing SARS-CoV-2 during the COVID pandemic. However, saliva collection has attracted attention as an alternative diagnostic collection method. The goal of this study was to compare the use of saliva and nasopharyngeal swab (NPS) samples for the detection of SARS-CoV-2. METHODS: Ninety-nine paired samples were evaluated for the detection of SARS-CoV-2 by saliva and swab for a qualitative diagnosis and quantitative comparison of viral particles. Furthermore, the detection limits for each sample collection technique were determined. The cycle threshold (CT) values of the saliva samples, the vaccination status, and the financial costs associated with each collection technique were compared. RESULTS: The results showed qualitative equivalence in diagnosis (96.96%) comparing saliva and swab collection, although there was low quantitative agreement. Furthermore, the detection limit test demonstrated equivalence for both collection methods. We did not observe a statistically significant association between CT values and vaccination status, indicating that the vaccine had no influence on viral load at diagnosis. Finally, we observed that the use of saliva incurs lower financial costs and requires less use of plastic materials, making it more sustainable. CONCLUSIONS: These findings support the adoption of saliva collection as a feasible and sustainable alternative to the diagnosis of COVID-19.

Quantitative SARS-CoV-2 RT-PCR and Bronchoalveolar Cytokine Concentrations Redefine the COVID-19 Phenotypes in Critically Ill Patients.

RATIONALE: Recent studies suggest that both hypo- and hyperinflammatory acute respiratory distress syndrome (ARDS) phenotypes characterize severe COVID-19-related pneumonia. The role of lung Severe Acute Respiratory Syndrome - Coronavirus 2 (SARS-CoV-2) viral load in contributing to these phenotypes remains unknown. OBJECTIVES: To redefine COVID-19 ARDS phenotypes when considering quantitative SARS-CoV-2 RT-PCR in the bronchoalveolar lavage of intubated patients. To compare the relevance of deep respiratory samples versus plasma in linking the immune response and the quantitative viral loads. METHODS: Eligible subjects were adults diagnosed with COVID-19 ARDS who required mechanical ventilation and underwent bronchoscopy. We recorded the immune response in the bronchoalveolar lavage and plasma and the quantitative SARS-CoV-2 RT-PCR in the bronchoalveolar lavage. Hierarchical clustering on principal components was applied separately on the 2 compartments' datasets. Baseline characteristics were compared between clusters. MEASUREMENTS AND RESULTS: Twenty subjects were enrolled between August 2020 and March 2021. Subjects underwent bronchoscopy on average 3.6 days after intubation. All subjects were treated with dexamethasone prior to bronchoscopy, 11 of 20 (55.6%) received remdesivir and 1 of 20 (5%) received tocilizumab. Adding viral load information to the classic 2-cluster model of ARDS revealed a new cluster characterized by hypoinflammatory responses and high viral load in 23.1% of the cohort. Hyperinflammatory ARDS was noted in 15.4% of subjects. Bronchoalveolar lavage clusters were more stable compared to plasma. CONCLUSIONS: We identified a unique group of critically ill subjects with COVID-19 ARDS who exhibit hypoinflammatory responses but high viral loads in the lower airways. These clusters may warrant different treatment approaches to improve clinical outcomes.

Association of viral loads of influenza A (H3N2) with age and care setting on presentation-a prospective study during the 2022-2023 influenza season in Spain.

OBJECTIVES: The aim of this study was to analyze the viral load (VL) using cycle threshold (Ct) in patients infected with influenza A (H3N2). METHODS: This prospective study was conducted during the 2022-2023 influenza season in sentinel, non-sentinel, and hospitalized patients of Castilla y León (Spain). Respiratory samples were obtained from nasopharyngeal swabs and analyzed by quantitative reverse transcription-polymerase chain reaction specific for influenza A (H3N2) to obtain the Ct value. RESULTS: A total of 1047 individuals were enrolled (174 [16.6%] sentinel, 200 [19.1%] non-sentinel, 673 [64.3%] hospitalized). The mean Ct value was lower in infants, young children, and in the elderly, with a sharp increase in the last from 65 years until 90 years. In addition, the lower Ct values were observed in non-sentinel patients and then in hospitalized patients, probably because non-sentinel are outpatients in the acute phase of the influenza infection. CONCLUSIONS: A higher VL (lower Ct value) is related to the extreme ages of life: children and the elderly. Furthermore, a higher VL is related with the care setting, being probably higher in outpatients because they are in the acute phase of the disease and slightly lower in hospitalized patients because they are attended during the post-acute phase.

The CoLab score is associated with SARS-CoV-2 viral load during admission in individuals admitted to the intensive care unit: the CoLaIC cohort study.

OBJECTIVES: The present study examines the temporal association between the changes in SARS-CoV-2 viral load during infection and whether the CoLab-score can facilitate de-isolation. METHODS: Nasal swabs and blood samples were collected from ICU-admitted SARS-CoV-2 positive patients at Maastricht UMC+ from March 25, 2020 to October 1, 2021. The CoLab-score was calculated based on 10 blood parameters and age and can range from -43 to 6. Three mixed effects analyses compared patient categories based on initial PCR Ct values (low; Ct≤20, mid; 20>Ct≤30, high; Ct>30), serial PCR Ct values to CoLab-scores over time, and the association between within-patient delta Ct values and CoLab-scores. RESULTS: In 324 patients, the median Ct was 33, and the median CoLab-score was -1.78. Mid (n=110) and low (n=41) Ct-categories had higher CoLab-scores over time (+0.60 points, 95 % CI; 0.04-1.17, and +0.28 points, 95 % CI -0.49 to 1.04) compared to the high Ct (n=87) category. Over time, higher serial Ct values were associated with lower serial CoLab-scores, decreasing by -0.07 points (95 % CI; -0.11 to -0.02) per day. Increasing delta Ct values were associated with a decreasing delta CoLab-score of -0.12 (95 % CI; -0.23; -0.01). CONCLUSIONS: The study found an association between lower viral load on admission and reduced CoLab-score. Additionally, a decrease in viral load over time was associated with a decrease in CoLab-score. Therefore, the CoLab-score may make patient de-isolation an option based on the CoLab-score.

SARS-CoV-2 Persistence in Immunocompromised Patients Requiring Treatment With Convalescent Plasma: A Case Report.

Severe acute respiratory syndrome-2 (SARS-CoV-2) infection in immunocompromised patients presents a challenge, as patients with such conditions may have severe courses. Identifying modalities to shorten the course or lessen the severity of infection could be potentially beneficial. A 76-year-old male with follicular lymphoma on rituximab and lenalidomide presented with COVID-19 pneumonia requiring intensive care unit (ICU) level care for persistent hypoxemia. He was treated with an extended course of remdesivir, as recommended by the Infectious Diseases service, but he maintained a persistently high viral load, necessitating a delay of his cancer treatment until he had recovered from his infection. On hospital day 31, he was given one dose of convalescent plasma with improvement in his SARS-CoV-2 viral load. He was able to be discharged and resumed cancer treatment soon thereafter. Convalescent plasma is a potential therapeutic option for immunocompromised patients with SARS-CoV-2 infection and should be considered early in the hospital course. Additionally, cycle threshold monitoring may be beneficial in certain scenarios: for instance to guide consideration of alternative therapies in patients with severe COVID-19 who have persistent symptoms and viremia while on guideline-directed therapy.

Determination of the cycle threshold value of the Xpert Xpress SARS-CoV-2/Flu/RSV test that corresponds to the presence of infectious SARS-CoV-2 in anterior nasal swabs.

Despite having high analytical sensitivities and specificities, qualitative SARS-CoV-2 nucleic acid amplification tests (NAATs) cannot distinguish infectious from non-infectious virus in clinical samples. In this study, we determined the highest cycle threshold (Ct) value of the SARS-CoV-2 targets in the Xpert Xpress SARS-CoV-2/Flu/RSV (Xpert 4plex) test that corresponded to the presence of detectable infectious SARS-CoV-2 in anterior nasal swab samples. A total of 111 individuals with nasopharyngeal swab specimens that were initially tested by the Xpert Xpress SARS-CoV-2 test were enrolled. A healthcare worker subsequently collected anterior nasal swabs from all SARS-CoV-2-positive individuals, and those specimens were tested by the Xpert 4plex test, viral culture, and laboratory-developed assays for SARS-CoV-2 replication intermediates. SARS-CoV-2 Ct values from the Xpert 4plex test were correlated with data from culture and replication intermediate testing to determine the Xpert 4plex assay Ct value that corresponded to the presence of infectious virus. Ninety-eight of the 111 (88.3%) individuals initially tested positive by the Xpert Xpress SARS-CoV-2 test. An anterior nasal swab specimen collected from positive individuals a median of 2 days later (range, 0-9 days) tested positive for SARS-CoV-2 by the Xpert 4plex test in 39.8% (39/98) of cases. Of these samples, 13 (33.3%) were considered to contain infectious virus based on the presence of cultivable virus and replication intermediates, and the highest Ct value observed for the Xpert 4plex test in these instances was 26.3. Specimens that yielded Ct values of ≤26.3 when tested by the Xpert 4plex test had a likelihood of containing infectious SARS-CoV-2; however, no infectious virus was detected in specimens with higher Ct values.IMPORTANCEUnderstanding the correlation between real-time PCR test results and the presence of infectious SARS-CoV-2 may be useful for informing patient management and workforce return-to-work or -duty. Further studies in different patient populations are needed to correlate Ct values or other biomarkers of viral replication along with the presence of infectious virus in clinical samples.