Diagnostic guidance for patients with persistent pulmonary abnormalities after COVID-19 infection: the potential benefit of 68Ga-FAPI PET/CT (preprint)

Coronavirus disease 2019 (COVID-19)-related pneumonia challenges clinical practice. We explore the potential diagnostic benefit of positron emission tomography/computed tomography (PET/CT) in order to establish the underlying inflammatory or fibrotic repair processes in prolonged structural lung abnormalities in COVID-19 patients.Methods: Six post-COVID-19 patients suspected for pulmonary fibrosis were scheduled for dual tracer PET/CT with 18 F-FDG (fluorodeoxyglucose) and 68Ga-fibroblast activation protein inhibitor (FAPI)-46. The uptake of 68 Ga FAPI-46  in the involved lung was compared to a control group of nine non COVID-19 patients. Clinical data and PET/CT imaging were collected and analysed.Results: PET/CT revealed in all six pulmonary impaired patients the reduced glucose avidity on 18 F-FDG and clear positivity on 68 Ga-FAPI-46 PET/CT in comparison to the control group. Conclusion: Indicating fibrotic repair mechanisms, 68 Ga-FAPI PET/CT may enhance non-invasive clinical diagnostic performance, drive therapeutic interventions, and facilitate therapeutic response monitoring in patients with long-term CT-abnormalities after severe COVID-19.

Phenotyping of acute and persistent COVID-19 features in the outpatient setting: exploratory analysis of an international cross-sectional online survey (preprint)

BACKGROUNDLong COVID, defined as presence of COVID-19 related symptoms 28 days or more after the onset of acute SARS-CoV-2 infection, is an emerging challenge to healthcare systems. The objective of this study was to phenotype recovery trajectories of non-hospitalized COVID-19 individuals. METHODSWe performed an international, multi-center, exploratory online survey study on demographics, comorbidities, COVID-19 symptoms and recovery status of non-hospitalized SARS-CoV-2 infected adults (Austria: n=1157), and Italy: n= 893). RESULTSWorking age subjects (Austria median: 43 yrs (IQR: 31 - 53), Italy: 45 yrs (IQR: 35 - 55)) and females (65.1% and 68.3%) predominated the study cohorts. Course of acute COVID-19 was characterized by a high symptom burden (median 13 (IQR: 9 - 18) and 13 (7 - 18) out of 44 features queried), a 47.6 - 49.3% rate of symptom persistence beyond 28 days and 20.9 - 31.9% relapse rate. By cluster analysis, two acute symptom phenotypes could be discerned: the non-specific infection phenotype and the multi-organ phenotype (MOP), the latter encompassing multiple neurological, cardiopulmonary, gastrointestinal and dermatological features. Clustering of long COVID subjects yielded three distinct subgroups, with a subset of 48.7 - 55 % long COVID individuals particularly affected by post-acute MOP symptoms. The number and presence of specific acute MOP symptoms and pre-existing multi-morbidity was linked to elevated risk of long COVID. CONCLUSIONThe consistent findings of two independent cohorts further delineate patterns of acute and post-acute COVID-19 and emphasize the importance of symptom phenotyping of home-isolated COVID-19 patients to predict protracted convalescence and to allocate medical resources. Key PointsO_ST_ABSQuestionC_ST_ABSWhich acute symptom patterns of acute COVID-19 are associated with prolonged symptom persistence, symptom relapse or physical performance impairment? FindingsIn this multicenter international comparative survey study on non-hospitalized SARS- CoV-2 infected adults (Austria: n = 1157, Italy: n = 893) we identified distinct and reproducible phenotypes of acute and persistent features. Acute multi-organ symptoms including neurological and cardiopulmonary manifestations are linked to elevated risk of long COVID. MeaningThese findings suggest to employ symptom phenotyping of home-isolated COVID-19 patients to predict protracted convalescence and to allocate medical resources.

A proteomic survival predictor for COVID-19 patients in intensive care (preprint)

Global healthcare systems are challenged by the COVID-19 pandemic. There is a need to optimize allocation of treatment and resources in intensive care, as clinically established risk assessments such as SOFA and APACHE II scores show only limited performance for predicting the survival of severely ill COVID-19 patients. Comprehensively capturing the host physiology, we speculated that proteomics in combination with new data-driven analysis strategies could produce a new generation of prognostic discriminators. We studied two independent cohorts of patients with severe COVID-19 who required intensive care and invasive mechanical ventilation. SOFA score, Charlson comorbidity index and APACHE II score were poor predictors of survival. Plasma proteomics instead identified 14 proteins that showed concentration trajectories different between survivors and non-survivors. A proteomic predictor trained on single samples obtained at the first time point at maximum treatment level (i.e. WHO grade 7) and weeks before the outcome, achieved accurate classification of survivors in an exploratory (AUROC 0.81) as well as in the independent validation cohort (AUROC of 1.0). The majority of proteins with high relevance in the prediction model belong to the coagulation system and complement cascade. Our study demonstrates that predictors derived from plasma protein levels have the potential to substantially outperform current prognostic markers in intensive care.

Clinical validation of the quantitative Siemens SARS-CoV-2 spike IgG assay (sCOVG) reveals improved sensitivity and a good correlation with virus neutralization titers (preprint)

ObjectivesSevere Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections cause Coronavirus Disease 2019 (COVID-19) and induce a specific antibody response. Serological assays detecting IgG against the receptor binding domain (RBD) of the spike (S) protein are useful to monitor the immune response after infection or vaccination. The objective of our study was to evaluate the clinical performance of the Siemens SARS-CoV-2 IgG (sCOVG) assay. MethodsSensitivity and specificity of the Siemens sCOVG test were evaluated on 178 patients with SARS-CoV-2-infection and 160 pre-pandemic samples in comparison with its predecessor test COV2G. Furthermore, correlation with virus neutralization titers was investigated on 134 samples of convalescent COVID-19 patients. ResultsSpecificity of the sCOVG test was 99.4% and sensitivity was 90.5% (COV2G assay 78.7%; p<0.0001). S1-RBD antibody levels showed a good correlation with virus neutralization titers (r=0.843; p<0.0001) and an overall qualitative agreement of 98.5%. Finally, median S1-RBD IgG levels increase with age and were significantly higher in hospitalized COVID-19 patients (median levels general ward: 25.7 U/ml; intensive care: 59.5 U/ml) than in outpatients (3.8 U/ml; p<0.0001). ConclusionsPerformance characteristics of the sCOVG assay have been improved compared to the predecessor test COV2G. Quantitative SARS-CoV-2 S1-RBD IgG levels could be used as a surrogate for virus neutralization capacity. Further harmonization of antibody quantification might assist to monitor the humoral immune response after COVID-19 disease or vaccination.

A comprehensive antigen production and characterization study for easy-to-implement, highly specific and quantitative SARS-CoV-2 antibody assays (preprint)

Antibody tests are essential tools to investigate humoral immunity following SARS-CoV-2 infection. While first-generation antibody tests have primarily provided qualitative results with low specificity, accurate seroprevalence studies and tracking of antibody levels over time require highly specific, sensitive and quantitative test setups. Here, we describe two quantitative ELISA antibody tests based on the SARS-CoV-2 spike receptor-binding domain and the nucleocapsid protein. Comparative expression in bacterial, insect, mammalian and plant-based platforms enabled the identification of new antigen designs with superior quality and high suitability as diagnostic reagents. Both tests scored excellently in clinical validations with multi-centric specificity and sensitivity cohorts and showed unprecedented correlation with SARS-CoV-2 neutralization titers. Orthogonal testing increased assay specificity to 99.8%, thereby enabling robust serodiagnosis in low-prevalence settings. The inclusion of a calibrator permits accurate quantitative monitoring of antibody concentrations in samples collected at different time points during the acute and convalescent phase of COVID-19.

Neurological Outcome and Quality of Life Three Months after COVID-19: A Prospective Observational Cohort Study (preprint)

BACKGROUND: Increasing evidence suggests the involvement of the central and peripheral nervous system in patients with coronavirus disease 2019 (COVID-19). Little is known about neurological outcomes and quality of life (QoL) after recovery from acute infection.METHODS: In this prospective, multicentre, observational cohort study we systematically evaluated neurological signs and diseases by detailed neurological examination and a predefined test battery assessing smelling disorders (16-item Sniffin-Sticks-test), cognitive deficits (Montreal Cognitive Assessment), QoL (36-item Short Form), and mental health (Hospital Anxiety and Depression Scale, Post-traumatic Stress Disorder Checklist-5) three months after disease onset.FINDINGS: Of 135 COVID-19 patients included, 31 (23%) required ICU-care (severe), 72 (53%) were admitted to the regular ward (moderate), and 32 (24%) underwent outpatient-care (mild) during acute disease. At three-month follow-up, 20 patients (15%) presented with one or more neurological syndromes that were not evident before COVID-19. These included poly-neuro/myopathy (n=16, 12%), mild encephalopathy (n=2, 2%), parkinsonism (n=1, 1%), orthostatic hypotension (n=1, 1%), Guillain-Barré-Syndrome (n=1, 1%) and ischemic stroke (n=1, 1%). Self-reported hyposmia/anosmia was noted in 23/135 patients (17%), which was significantly lower compared to those documented during acute COVID-19 (44%; p<0·001). Interestingly, objective testing revealed hyposmia/anosmia in 57/127 (45%) patients at three-month follow-up. In ICU patients, encephalopathy significantly improved over time (from 29% (9/31) during acute disease to 3% (1/31) at follow-up, p=0·008). At follow-up, cognitive deficits were apparent in 23% (29/124), and QoL was impaired in 31% (28/90). Assessment of mental health revealed symptoms of depression, anxiety and post-traumatic stress disorders in 11%, 25%, and 11%, respectively.INTERPRETATION: Despite recovery from acute infection, neurological symptoms were prevalent at three-months follow-up. Above all, smelling disorders were persistent in a large proportion of patients. Our results urge for further studies investigating the onset and evolution of neurological diseases following COVID-19 infection to develop strategies for secondary prevention.TRIAL REGISTRATION: ClinicalTrials.gov (NCT04416100)FUNDING: Not applicable.DECLARATION OF INTERESTS: KS reports grants from FWF Austrian Science Fund, grants from Michael J. Fox Foundation, grants from International Parkinson and Movement Disorder Society, personal fees from Teva, personal fees from UCB, personal fees from Lundbeck, personal fees from AOP Orphan Pharmaceuticals AG, personal fees from Abbvie, personal fees from Roche, personal fees from Grünenthal; all outside the submitted work. PM reports grants from TWF (Tyrolean Science Fund), grants from Medtronic, personal fees from Boston Scientific, all outside the submitted work. The other authors have nothing to disclose. All other authors declare no competing interests.ETHICS APPROVAL STATEMENT: The conduct of the study was approved by the local ethics committee (Medical University of Innsbruck, EK Nr: 1103/2020). Written informed consent was obtained from all patients according to local regulations.

Evaluation of four commercial, fully automated SARS-CoV-2 antibody tests suggests a revision of the Siemens SARS-CoV-2 IgG assay (preprint)

ObjectivesSerological tests detect antibodies against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in the ongoing coronavirus disease-19 (COVID-19) pandemic. Independent external clinical validation of performance characteristics is of paramount importance. MethodsFour fully automated assays, Roche Elecsys Anti-SARS-CoV-2, Abbott SARS-CoV-2 IgG, Siemens SARS-CoV-2 total (COV2T) and SARS-CoV-2 IgG (COV2G) were evaluated using 350 pre-pandemic samples and 700 samples from 245 COVID-19 patients (158 hospitalized, 87 outpatients). ResultsAll tests showed very high diagnostic specificity. Sensitivities in samples collected at least 14 days after disease onset were slightly lower than manufacturers claims for Roche (93.04%), Abbott (90.83%), and Siemens COV2T (90.26%), and distinctly lower for Siemens COV2G (78.76%). Concordantly negative results were enriched for immunocompromised patients. ROC curve analyses suggest a lowering of the cut-off index for the Siemens COV2G assay. Finally, the combination of two anti-SARS-CoV-2 antibody assays is feasible when considering borderline reactive results. ConclusionsThorough on-site evaluation of commercially available serologic tests for detection of antibodies against SARS-CoV-2 remains imperative for laboratories. The potentially impaired sensitivity of the Siemens COV2G necessitates a switch to the companys newly filed SARS-CoV-2 IgG assay (sCOVG) for follow-up studies. A combination of tests could be considered in clinical practice.