COI vs Ct: comparing automated antigen tests cut-off index (COI) to PCR cycle threshold (Ct)

Introduction: The objective of this study was to compare the numeric cut-off index (COI) of automated antigen tests with the cycle-threshold (Ct) value. Materials and methods: COI values of all samples processed with the Elecsys® SARS-CoV-2 Antigen (Roche, Switzerland) from January to February 2022 were retrieved and the positive were compared to RdRP Cts of Allplex Variants I (Seegene, Korea). COI between 0.6 and 1 were considered indeterminate and overproved by RT-PCR. Results: From 13,937 samples 7944(57%) were positive and 189(1.35%) indeterminate. There was a strong correlation between Cts and COI values at the positive samples, but that was not the case for indeterminates. Conclusions: COI values of the positive samples (COI >1) are comparable to Ct values and may therefore be used as proxy viral loads, however this is not the case for indeterminate samples. © 2022 Elsevier Inc.

Long COVID following mild SARS-CoV-2 infection: characteristic T cell alterations and response to antihistamines.

Long COVID is characterized by the emergence of multiple debilitating symptoms following SARS-CoV-2 infection. Its etiology is unclear and it often follows a mild acute illness. Anecdotal reports of gradual clinical responses to histamine receptor antagonists (HRAs) suggest a histamine-dependent mechanism that is distinct from anaphylaxis, possibly mediated by T cells, which are also regulated by histamine. T cell perturbations have been previously reported in post-viral syndromes, but the T cell landscape in patients who have recovered from mild COVID-19 and its relationship to both long COVID symptoms and any symptomatic response to HRA remain underexplored. We addressed these questions in an observational study of 65 individuals who had recovered from mild COVID-19. Participants were surveyed between 87 and 408 days after the onset of acute symptoms; none had required hospitalization, 16 had recovered uneventfully, and 49 had developed long COVID. Symptoms were quantified using a structured questionnaire and T cell subsets enumerated in a standard diagnostic assay. Patients with long-COVID had reduced CD4+ and CD8+ effector memory (EM) cell numbers and increased PD-1 (programmed cell death protein 1) expression on central memory (CM) cells, whereas the asymptomatic participants had reduced CD8+ EM cells only and increased CD28 expression on CM cells. 72% of patients with long COVID who received HRA reported clinical improvement, although T cell profiling did not clearly distinguish those who responded to HRA. This study demonstrates that T cell perturbations persist for several months after mild COVID-19 and are associated with long COVID symptoms.

Performance of Antigen-Based Testing as Frontline Diagnosis of Symptomatic COVID-19.

Background and Objectives: To evaluate the performance of antigen-based detection tests as the frontline diagnosis of coronavirus disease 2019 (COVID-19). Materials and Methods: We conducted a nationwide retrospective cohort study in Mexico. A cross-sectional analysis of a cohort study was conducted in Mexico and data from 15,408 suspected (all of them symptomatic) cases of COVID-19 were analyzed. The results of antigen-based tests were compared with those obtained by molecular (polymerase chain reaction-based) assays. Results: The antigen-based tests showed sensitivity below 50% and high specificity in all the analyzed age groups. The highest Youden index (J) was observed among adults aged 25-44 years old (45.5, 95% CI 43.7-47.3). Conclusions: We documented the poor performance of serologic techniques as frontline diagnosis of symptomatic COVID-19 and inaccurate results may impact negatively on pandemic progression.

Graft survival effect of HLA-A allele matching parathyroid allotransplantation.

Permanent hypoparathyroidism is an endocrine disease that is mostly associated with the disruption of the parathyroid glands during surgery. Allotransplantation is the most promising approach for treatment particularly for its cost-effective and exact curative potential. Herein our aim was to evaluate human leukocyte antigen (HLA)-A allele matching effect on clinical improvement and graft survival after parathyroid transplantation. We performed parathyroid transplantation between ABO/Rh compatible recipient and an unrelated donor who has chronic kidney disease. Preoperative immunological tests include panel reactive antibody, T-flow cytometry crossmatch, B-flow cytometry crossmatch, autoflow cytometry crossmatch, and complement-dependent cytotoxicity crossmatch tests were performed. After histopathological evaluation, half of the resected parathyroid gland cells were isolated and transplanted to the omentum surface by laparoscopy. The transplantation outcome was followed up throughout 382 days. The recipient discharged 2 days after transplantation without any complication. During follow-up, calcium and vitamin D supplementation reduced to a one-third dose; even the intact PTH levels remained low. However, clinical improvement was observed by serum calcium levels. The recipient still continues with low-dose supplementation after 382 days of post-transplantation. Parathyroid cell transplantation to the omental tissue is the most promising option even with only one allele matching for patients with using lifelong high-dose supplementation. Clinical improvements and long-term effect of HLA-A allele matching should be evaluated with more studies and in larger cohorts as well.

COVID-19: clinical and laboratory manifestations in novel coronavirus infection / COVID-19: manifestações clínicas e laboratoriais na infecção pelo novo coronavírus

ABSTRACT COVID-19 is a highly contagious disease caused by the coronavirus of severe acute respiratory syndrome 2 (SARS-CoV-2). In 2020, due to the outbreak, it was considered by the World Health Organization (WHO) as a pandemic. The infection caused by the novel coronavirus has high mortality in a small portion of the infected population, especially in elderly, immunosuppressed, diabetic, cardiac, and hypertensive individuals. Many infected are asymptomatic (and may be carriers) or present mild or moderate flu-like symptoms. The most severe clinical picture of COVID-19 is characterized by an inflammatory cytokine storm, with hematological changes and coagulation dysfunction, which can lead to tissue damage and death. Nonspecific laboratory biomarkers may be either increased or decreased as the course of the disease progresses and are often useful in predicting complications of the disease, such as the use of D-dimer and platelet/lymphocyte ratio. Specific laboratory diagnosis is based on the detection of viral ribonucleic acid (RNA) by real-time polymerase chain reaction (RT-PCR) of nasal and oropharyngeal swab samples; it is more effective when performed in the first days after symptom onset. Serological tests are useful in detecting the immune response, since both class M (IgM) and class G (IgG) immunoglobulin antibodies can be detected seven days after the onset of clinical symptoms, and may extend for more than 25 days, although not exempting the individual from remaining infectious, depending on their viral load and clinical presentation. The rational use of specific laboratory markers must respect the disease chronology, and the correct interpretation may provide subsidies for a better management of affected patients, as well as identifying asymptomatic carriers or those with mild symptoms.

RESUMEN La COVID-19 es una enfermedad altamente contagiosa causada por el coronavirus del síndrome respiratorio agudo grave (SARS-CoV-2). En 2002, a causa del brote, fue reconocida como una pandemia por la Organización Mundial de la Salud (OMS). La infección por el nuevo coronavirus provoca alta mortalidad en una pequeña parcela de la población infectada, especialmente en ancianos, pacientes inmunodeprimidos, diabéticos, cardiópatas e hipertensos. Muchos infectados son asintomáticos (y pueden ser portadores) o presentan síntomas leves a moderados, como en un estado gripal. El cuadro clínico de la COVID-19 en la forma más grave es caracterizado por una tormenta inflamatoria de citoquinas, con cambios hematológicos y de la coagulación que pueden llevar a daño tisular y muerte. Pruebas de laboratorio inespecíficas pueden presentar tasas más altas o bajas según el curso de la enfermedad, y muchas veces son útiles en la predicción de complicaciones, como el uso del dímero D y la ratio plaquetas/linfocitos. El diagnóstico de laboratorio específico se basa en la detección del ácido ribonucleico (ARN) viral por reacción en cadena de la polimerasa (PCR) en tiempo real de muestras de hisopado nasal y orofaríngeo; es más efectiva en los primeros días tras el inicio de los síntomas. Pruebas serológicas son útiles para detectar la respuesta inmune, pues tanto los anticuerpos de la inmunoglobulina M (IgM) como de la G (IgG) pueden se detectar siete días después del inicio de los síntomas clínicos, y pueden permanecer por más de 25 días, aunque no eximen al individuo de seguir infeccioso, dependiendo de su carga viral y presentación clínica. El uso racional de los marcadores de laboratorio específicos debe respetar la cronología de la enfermedad, y la interpretación correcta puede proporcionar recursos para un mejor manejo de los pacientes afectados, así como identificar portadores asintomáticos o con pocos síntomas.

RESUMO COVID-19 é uma doença altamente contagiosa provocada pelo coronavírus da síndrome respiratória aguda grave 2 (SARS-CoV-2). Em 2020, devido ao surto, foi caracterizada pela Organização Mundial da Saúde (OMS) como pandemia. A infecção causada pelo novo coronavírus tem alta mortalidade em uma pequena parcela da população infectada, especialmente em indivíduos idosos, imunodeprimidos, diabéticos, cardiopatas e hipertensos. Muitos infectados são assintomáticos (e podem ser portadores) ou apresentam sintomas leves a moderados, semelhantes ao estado gripal. O quadro clínico da COVID-19 na forma mais severa é caracterizado por uma tempestade inflamatória de citocinas, com alterações hematológicas e da coagulação que podem levar ao dano tecidual e morte. Exames laboratoriais inespecíficos podem apresentar-se mais elevados ou diminuídos conforme o curso da doença, e muitas vezes são úteis na predição de complicações, como o uso do D-dímero e a razão plaqueta/linfócitos. O diagnóstico laboratorial específico se baseia na detecção do ácido ribonucleico (RNA) viral por reação em cadeia da polimerase em tempo real (RT-PCR) de amostras de suabe nasal e orofaríngeo; é mais efetivo nos primeiros dias após o início dos sintomas. Testes sorológicos são úteis na detecção da resposta imune, pois tanto os anticorpos da imunoglobulina da classe M (IgM) quanto da classe G (IgG) podem ser detectados após sete dias do início dos sintomas clínicos, podendo se estender por mais de 25 dias, embora não isente o indivíduo de continuar infectante, dependendo de sua carga viral e apresentação clínica. O uso racional dos marcadores laboratoriais específicos deve respeitar a cronologia da doença, e a interpretação correta pode fornecer subsídios para um melhor manejo dos pacientes acometidos, bem como identificar portadores assintomáticos ou com pouco sintomas.

Immune response to SARS-CoV-2 and mechanisms of immunopathological changes in COVID-19.

As a zoonotic disease that has already spread globally to several million human beings and possibly to domestic and wild animals, eradication of coronavirus disease 2019 (COVID-19) appears practically impossible. There is a pressing need to improve our understanding of the immunology of this disease to contain the pandemic by developing vaccines and medicines for the prevention and treatment of patients. In this review, we aim to improve our understanding on the immune response and immunopathological changes in patients linked to deteriorating clinical conditions such as cytokine storm, acute respiratory distress syndrome, autopsy findings and changes in acute-phase reactants, and serum biochemistry in COVID-19. Similar to many other viral infections, asymptomatic disease is present in a significant but currently unknown fraction of the affected individuals. In the majority of the patients, a 1-week, self-limiting viral respiratory disease typically occurs, which ends with the development of neutralizing antiviral T cell and antibody immunity. The IgM-, IgA-, and IgG-type virus-specific antibodies levels are important measurements to predict population immunity against this disease and whether cross-reactivity with other coronaviruses is taking place. High viral load during the first infection and repeated exposure to virus especially in healthcare workers can be an important factor for severity of disease. It should be noted that many aspects of severe patients are unique to COVID-19 and are rarely observed in other respiratory viral infections, such as severe lymphopenia and eosinopenia, extensive pneumonia and lung tissue damage, a cytokine storm leading to acute respiratory distress syndrome, and multiorgan failure. Lymphopenia causes a defect in antiviral and immune regulatory immunity. At the same time, a cytokine storm starts with extensive activation of cytokine-secreting cells with innate and adaptive immune mechanisms both of which contribute to a poor prognosis. Elevated levels of acute-phase reactants and lymphopenia are early predictors of high disease severity. Prevention of development to severe disease, cytokine storm, acute respiratory distress syndrome, and novel approaches to prevent their development will be main routes for future research areas. As we learn to live amidst the virus, understanding the immunology of the disease can assist in containing the pandemic and in developing vaccines and medicines to prevent and treat individual patients.