Peripheral HLA-G/ILT-2 immune checkpoint axis in acute and convalescent COVID-19 patients.

The immunosuppressive non-classical human leukocyte antigen-G (HLA-G) can elicits pro-viral activities by down-modulating immune responses. We analysed soluble forms of HLA-G, IL-6 and IL-10 as well as on immune effector cell expression of HLA-G and its cognate ILT-2 receptor in peripheral blood obtained from hospitalised and convalescent COVID-19 patients. Compared with convalescents (N = 202), circulating soluble HLA-G levels (total and vesicular-bound molecules) were significantly increased in hospitalised patients (N = 93) irrespective of the disease severity. During COVID-19, IL-6 and IL-10 levels were also elevated. Regarding the immune checkpoint expression of HLA-G/ILT-2 on peripheral immune effector cells, the frequencies of membrane-bound HLA-G on CD3+ and CD14+ cells were almost identical in patients during and post COVID-19, while the frequency of ILT-2 receptor on CD3+ and CD14+ cells was increased during acute infection. A multi-parametric correlation analysis of soluble HLA-G forms with IL-6, IL-10, activation markers CD25 and CD154, HLA-G, and ILT-2 expression on immune cells revealed a strong positive correlation of soluble HLA-G forms with membrane-bound HLA-G molecules on CD3+/CD14+ cells only in convalescents. During COVID-19, only vesicular-bound HLA-G were positively correlated with the activation marker CD25 on T cells. Thus, our data suggest that the elevated levels of soluble HLA-G in COVID-19 are due to increased expression in organ tissues other than circulating immune effector cells. The concomitant increased expression of soluble HLA-G and ILT-2 receptor frequencies supports the concept that the immune checkpoint HLA-G/ILT-2 plays a role in the immune-pathogenesis of COVID-19.

SARS-CoV-2 infection in chronic kidney disease patients with pre-existing dialysis: description across different pandemic intervals and effect on disease course (mortality).

PURPOSE: Patients suffering from chronic kidney disease (CKD) are in general at high risk for severe coronavirus disease (COVID-19) but dialysis-dependency (CKD5D) is poorly understood. We aimed to describe CKD5D patients in the different intervals of the pandemic and to evaluate pre-existing dialysis dependency as a potential risk factor for mortality. METHODS: In this multicentre cohort study, data from German study sites of the Lean European Open Survey on SARS-CoV-2-infected patients (LEOSS) were used. We multiply imputed missing data, performed subsequent analyses in each of the imputed data sets and pooled the results. Cases (CKD5D) and controls (CKD not requiring dialysis) were matched 1:1 by propensity-scoring. Effects on fatal outcome were calculated by multivariable logistic regression. RESULTS: The cohort consisted of 207 patients suffering from CKD5D and 964 potential controls. Multivariable regression of the whole cohort identified age (> 85 years adjusted odds ratio (aOR) 7.34, 95% CI 2.45-21.99), chronic heart failure (aOR 1.67, 95% CI 1.25-2.23), coronary artery disease (aOR 1.41, 95% CI 1.05-1.89) and active oncological disease (aOR 1.73, 95% CI 1.07-2.80) as risk factors for fatal outcome. Dialysis-dependency was not associated with a fatal outcome-neither in this analysis (aOR 1.08, 95% CI 0.75-1.54) nor in the conditional multivariable regression after matching (aOR 1.34, 95% CI 0.70-2.59). CONCLUSIONS: In the present multicentre German cohort, dialysis dependency is not linked to fatal outcome in SARS-CoV-2-infected CKD patients. However, the mortality rate of 26% demonstrates that CKD patients are an extreme vulnerable population, irrespective of pre-existing dialysis-dependency.

COVID-19 associated acute transplant failure after AB0-incompatible living donor kidney transplantation - a case report.

INTRODUCTION: Immunosuppressive therapy is associated with an increased risk of severe courses of SARS-CoV-2 infection, with frequently delayed viral clearance. We report a case of an acute kidney transplant failure in persistent SARS-CoV-2 infection in a patient with absolute B-cell depletion after administration of rituximab for AB0-incompatible living donor kidney transplantation. CASE PRESENTATION: A 34-year-old unvaccinated patient is diagnosed with SARS-CoV-2 infection four months after kidney transplantation. With only mild symptoms and an estimated glomerular filtration rate (eGFR) of 44 ml/min/1.73 m2, therapy with molnupiravir was initially given. Within the next eight weeks, transplant biopsies were performed for acute graft failure. These showed acute T-cell rejection with severe acute tubular epithelial damage with only mild interstitial fibrosis and tubular atrophy (BANFF cat. 4 IB), and borderline rejection (BANFF cat. 3). A therapy with prednisolone and intravenous immunoglobulins was performed twice. With unchanged graft failure, the third biopsy also formally showed BANFF cat. 4 IB. However, fluorescence in situ hybridization detected SARS-CoV-2 viruses in large portions of the distal tubules. After nine weeks of persistent COVID-19 disease neither anti-SARS-CoV-2 IgG nor a SARS-CoV-2-specific cellular immune response could be detected, leading to the administration of sotrovimab and remdesivir. Among them, SARS-CoV-2 clearance, detection of IgG, and improvement of graft function were achieved. CONCLUSION: Lack of viral clearance can lead to complications of SARS-CoV-2 infection with atypical manifestations. In kidney transplant patients, before initiating therapy, the differential diagnoses of "rejection" and "virus infection" should be weighed against each other in an interdisciplinary team of nephrologists, infectious diseases specialists and pathologists.

Superior humoral immunity in vaccinated SARS-CoV-2 convalescence as compared to SARS-COV-2 infection or vaccination.

Emerging variants of concern (VOC) raise obstacles in shaping vaccination strategies and ending the pandemic. Vaccinated SARS-CoV-2 convalescence shapes the current immune dynamics. We analyzed the SARS-CoV-2 VOC-specific cellular and humoral response of 57 adults: 42 convalescent mRNA vaccinated patients (C+V+), 8 uninfected mRNA vaccinated (C-V+) and 7 unvaccinated convalescent individuals (C+V-). While C+V+ demonstrated a superior humoral SARS-CoV-2 response against all analyzed VOC (alpha, delta, omicron) compared to C-V+ and C+V-, SARS-CoV-2 reactive CD4+ and CD8+ T cells, which can cross-recognize the alpha, delta and omicron VOC after infection and/or vaccination were observed in all there groups without significant differences between the groups. We observed a preserved cross-reactive C+V+ and C-V+ T cell memory. An inferior humoral response but preserved cross-reactive T cell memory in C+V- compared to C+V+ was observed, as well as an inferior humoral response but preserved cross-reactive T cell memory in C+V- compared to C-V+. Adaptive immunity generated after SARS-CoV-2 infection and vaccination leads to superior humoral immune response against VOC compared to isolated infection or vaccination. Despite the apparent loss of neutralization potential caused by viral evolution, a preserved SARS-CoV-2 reactive T cell response with a robust potential for cross-recognition of the alpha, delta and omicron VOC was detected in all studied cohorts. Our results may have implications on current vaccination strategies.

Evaluation of a new COVID-19 triage algorithm in the emergency department including combined antigen and PCR-testing: A case-control study.

The coronavirus disease 2019 (COVID-19) pandemic is a major challenge for global healthcare systems. Early and safe triage in the emergency department (ED) is crucial for proper therapy. However, differential diagnosis remains challenging. Rapid antigen testing (RAT) may help to improve early triage and patient safety. We performed a retrospective study of 234 consecutive patients with suspected COVID-19 who presented to our ED in November 2020. All underwent SARS-CoV-2-nasopharyngeal swab testing using both RAT and reverse transcription polymerase chain reaction (RT-PCR). The inpatient treatment was established according to an empirically developed triage algorithm. The accuracy of the suggested algorithm was analyzed based on the rate of outpatients returning within 7 days and inpatients staying for less than 48 hours. COVID-19 inpatients and outpatients were compared for symptoms, vital signs, and C-reactive protein levels. Of the 221 included patients with suspected COVID-19 infection, the diagnosis could be confirmed in 120 patients (54.3%) by a positive RT-PCR result, whereas only 72% of those had a positive antigen test. Of the 56 COVID-19 outpatients, three returned within 7 days with the need for hospital treatment due to clinical deterioration. Among the 64 COVID-19 inpatients, 4 were discharged within 48 hours, whereas 60 stayed longer (mean duration 10.2 days). The suggested triage algorithm was safe and efficient in the first 234 consecutive patients. RAT can confirm a diagnosis in 72% of PCR proven COVID-19 patients and allows early cohort isolation as an important way to save hospital capacity.

The Fungal Gut Microbiome Exhibits Reduced Diversity and Increased Relative Abundance of Ascomycota in Severe COVID-19 Illness and Distinct Interconnected Communities in SARS-CoV-2 Positive Patients.

Clinical and experimental studies indicate that the bacterial and fungal gut microbiota modulates immune responses in distant organs including the lungs. Immune dysregulation is associated with severe SARS-CoV-2 infection, and several groups have observed gut bacterial dysbiosis in SARS-CoV-2 infected patients, while the fungal gut microbiota remains poorly defined in these patients. We analyzed the fungal gut microbiome from rectal swabs taken prior to anti-infective treatment in 30 SARS-CoV-2 positive (21 non-severe COVID-19 and 9 developing severe/critical COVID-19 patients) and 23 SARS-CoV-2 negative patients by ITS2-sequencing. Pronounced but distinct interconnected fungal communities distinguished SARS-CoV-2 positive and negative patients. Fungal gut microbiota in severe/critical COVID-19 illness was characterized by a reduced diversity, richness and evenness and by an increase of the relative abundance of the Ascomycota phylum compared with non-severe COVID-19 illness. A dominance of a single fungal species with a relative abundance of >75% was a frequent feature in severe/critical COVID-19. The dominating fungal species were highly variable between patients even within the groups. Several fungal taxa were depleted in patients with severe/critical COVID-19.The distinct compositional changes of the fungal gut microbiome in SARS-CoV-2 infection, especially in severe COVID-19 illness, illuminate the necessity of a broader approach to investigate whether the differences in the fungal gut microbiome are consequences of SARS-CoV-2 infection or a predisposing factor for critical illness.

Severe Acute Respiratory Syndrome Coronavirus 2 Cross-Reactive B and T Cell Responses in Kidney Transplant Patients.

BACKGROUND: Immune responses to seasonal endemic coronaviruses might have a pivotal role in protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Those SARS-CoV-2-crossreactive T cells were recently described in immunocompetent individuals. Still, data on cross-reactive humoral and cellular immunity in kidney transplant recipients is currently lacking. METHODS: The pre-existing, cross-reactive antibody B and T cell immune responses against SARS-CoV-2 in unexposed adults with kidney transplantation (Tx, n = 14) and without (non-Tx, n = 12) sampled before the pandemic were compared with 22 convalescent patients with COVID-19 (Cp) applying enzyme-linked immunosorbent assay and flow cytometry. RESULTS: In both unexposed groups, SARS-CoV-2 IgG antibodies were not detectable. Memory B cells binding spike (S) protein SARS-CoV-2 were detected in unexposed individuals (64% among Tx; 50% among non-Tx) and higher frequencies after infection (80% Cp). The numbers of SARS-CoV-2-reactive T cells were comparable between patients who had undergone Tx and those who had not. SARS-CoV-2-reactive follicular T helper cells were present in 61% of the unexposed cohort in both patients who had undergone Tx and those who had not. CONCLUSIONS: Cross-reactive memory B and T cells against SARS-CoV-2 exist also in transplanted adults, suggesting a primed adaptive immunity. The effect on the disease course may depend on the concomitant immunosuppressive drugs.

Immune Response in Moderate to Critical Breakthrough COVID-19 Infection After mRNA Vaccination.

SARS-CoV-2 variants of concern (VOCs) can trigger severe endemic waves and vaccine breakthrough infections (VBI). We analyzed the cellular and humoral immune response in 8 patients infected with the alpha variant, resulting in moderate to fatal COVID-19 disease manifestation, after double mRNA-based anti-SARS-CoV-2 vaccination. In contrast to the uninfected vaccinated control cohort, the diseased individuals had no detectable high-avidity spike (S)-reactive CD4+ and CD8+ T cells against the alpha variant and wild type (WT) at disease onset, whereas a robust CD4+ T-cell response against the N- and M-proteins was generated. Furthermore, a delayed alpha S-reactive high-avidity CD4+ T-cell response was mounted during disease progression. Compared to the vaccinated control donors, these patients also had lower neutralizing antibody titers against the alpha variant at disease onset. The delayed development of alpha S-specific cellular and humoral immunity upon VBI indicates reduced immunogenicity against the S-protein of the alpha VOC, while there was a higher and earlier N- and M-reactive T-cell response. Our findings do not undermine the current vaccination strategies but underline a potential need for the inclusion of VBI patients in alternative vaccination strategies and additional antigenic targets in next-generation SARS-CoV-2 vaccines.

[Wave riding - 12 months of COVID-19 in a German tertiary care center]. / Wellenreiten ­ 12 Monate COVID-19 im Maximalversorger.

INTRODUCTION: With more than 1400 COVID-19 inpatients, the university hospital of Essen is the main regional caregiver during COVID-19 pandemic. We present outcome data of our inpatients during the first 12 months of pandemic and our derived clinical care concepts. METHODS: Retrospective analysis of all 1396 COVID-19 inpatients presenting between March, 1st of 2020 and February, 28th of 2021 for comorbidities, survival and complications. Group comparison between patients receiving standard care and those requiring intermediate/ intensive care. RESULTS: Mortality rate of all inpatients was 19,8 % (277/ 1396), whereas 10.6 % (93/877) of the patients with standard care and 35.5 % (184/519) of those with intermediate/intensive care died during hospital stay. Age above 60 years, obesity, need for mechanical ventilation, nitric oxide therapy, ECMO and acute renal failure as well as stroke during the clinical course were independent predictors of mortality. CONCLUSIONS: The mortality of both patient groups ranges within the numbers published by other international groups. The vast impact of usual comorbidities could be observed as well as the high rate of complications in serious ill COVID-19 patients. The mean age of both patient groups was lower than expected (60 years standard care versus 63 years intermediate/ intensive care). A maximum of patient and staff protection measures, a fast and efficient testing strategy during primary triage, standardized concepts from emergency department to intensive care units and dynamic adjustment of resources to daily changing needs can ensure a high quality of care even during peak of pandemic.

A Pro-Inflammatory Gut Microbiome Characterizes SARS-CoV-2 Infected Patients and a Reduction in the Connectivity of an Anti-Inflammatory Bacterial Network Associates With Severe COVID-19.

The gut microbiota contributes to maintaining human health and regulating immune responses. Severe COVID-19 illness is associated with a dysregulated pro-inflammatory immune response. The effect of SARS-CoV-2 on altering the gut microbiome and the relevance of the gut microbiome on COVID-19 severity needs to be clarified. In this prospective study, we analyzed the gut microbiome of 212 patients of a tertiary care hospital (117 patients infected with SARS-CoV-2 and 95 SARS-CoV-2 negative patients) using 16S rRNA gene sequencing of the V3-V4 region. Inflammatory markers and immune cells were quantified from blood. The gut microbiome in SARS-CoV-2 infected patients was characterized by a lower bacterial richness and distinct differences in the gut microbiome composition, including an enrichment of the phyla Proteobacteria and Bacteroidetes and a decrease of Actinobacteria compared to SARS-CoV-2 negative patients. The relative abundance of several genera including Bifidobacterium, Streptococcus and Collinsella was lower in SARS-CoV-2 positive patients while the abundance of Bacteroides and Enterobacteriaceae was increased. Higher pro-inflammatory blood markers and a lower CD8+ T cell number characterized patients with severe COVID-19 illness. The gut microbiome of patients with severe/critical COVID-19 exhibited a lower abundance of butyrate-producing genera Faecalibacterium and Roseburia and a reduction in the connectivity of a distinct network of anti-inflammatory genera that was observed in patients with mild COVID-19 illness and in SARS-CoV-2 negative patients. Dysbiosis of the gut microbiome associated with a pro-inflammatory signature may contribute to the hyperinflammatory immune response characterizing severe COVID-19 illness.

Development and validation of a simplified risk score for the prediction of critical COVID-19 illness in newly diagnosed patients.

Scores to identify patients at high risk of progression of coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), may become instrumental for clinical decision-making and patient management. We used patient data from the multicentre Lean European Open Survey on SARS-CoV-2-Infected Patients (LEOSS) and applied variable selection to develop a simplified scoring system to identify patients at increased risk of critical illness or death. A total of 1946 patients who tested positive for SARS-CoV-2 were included in the initial analysis and assigned to derivation and validation cohorts (n = 1297 and n = 649, respectively). Stability selection from over 100 baseline predictors for the combined endpoint of progression to the critical phase or COVID-19-related death enabled the development of a simplified score consisting of five predictors: C-reactive protein (CRP), age, clinical disease phase (uncomplicated vs. complicated), serum urea, and D-dimer (abbreviated as CAPS-D score). This score yielded an area under the curve (AUC) of 0.81 (95% confidence interval [CI]: 0.77-0.85) in the validation cohort for predicting the combined endpoint within 7 days of diagnosis and 0.81 (95% CI: 0.77-0.85) during full follow-up. We used an additional prospective cohort of 682 patients, diagnosed largely after the "first wave" of the pandemic to validate the predictive accuracy of the score and observed similar results (AUC for the event within 7 days: 0.83 [95% CI: 0.78-0.87]; for full follow-up: 0.82 [95% CI: 0.78-0.86]). An easily applicable score to calculate the risk of COVID-19 progression to critical illness or death was thus established and validated.

Neurological symptoms and complications in predominantly hospitalized COVID-19 patients: Results of the European multinational Lean European Open Survey on SARS-Infected Patients (LEOSS).

BACKGROUND AND PURPOSE: During acute coronavirus disease 2019 (COVID-19) infection, neurological signs, symptoms and complications occur. We aimed to assess their clinical relevance by evaluating real-world data from a multinational registry. METHODS: We analyzed COVID-19 patients from 127 centers, diagnosed between January 2020 and February 2021, and registered in the European multinational LEOSS (Lean European Open Survey on SARS-Infected Patients) registry. The effects of prior neurological diseases and the effect of neurological symptoms on outcome were studied using multivariate logistic regression. RESULTS: A total of 6537 COVID-19 patients (97.7% PCR-confirmed) were analyzed, of whom 92.1% were hospitalized and 14.7% died. Commonly, excessive tiredness (28.0%), headache (18.5%), nausea/emesis (16.6%), muscular weakness (17.0%), impaired sense of smell (9.0%) and taste (12.8%), and delirium (6.7%) were reported. In patients with a complicated or critical disease course (53%) the most frequent neurological complications were ischemic stroke (1.0%) and intracerebral bleeding (ICB; 2.2%). ICB peaked in the critical disease phase (5%) and was associated with the administration of anticoagulation and extracorporeal membrane oxygenation (ECMO). Excessive tiredness (odds ratio [OR] 1.42, 95% confidence interval [CI] 1.20-1.68) and prior neurodegenerative diseases (OR 1.32, 95% CI 1.07-1.63) were associated with an increased risk of an unfavorable outcome. Prior cerebrovascular and neuroimmunological diseases were not associated with an unfavorable short-term outcome of COVID-19. CONCLUSION: Our data on mostly hospitalized COVID-19 patients show that excessive tiredness or prior neurodegenerative disease at first presentation increase the risk of an unfavorable short-term outcome. ICB in critical COVID-19 was associated with therapeutic interventions, such as anticoagulation and ECMO, and thus may be an indirect complication of a life-threatening systemic viral infection.

Angiotensin II receptor blocker intake associates with reduced markers of inflammatory activation and decreased mortality in patients with cardiovascular comorbidities and COVID-19 disease.

AIMS: Patients with cardiovascular comorbidities have a significantly increased risk for a critical course of COVID-19. As the SARS-CoV2 virus enters cells via the angiotensin-converting enzyme receptor II (ACE2), drugs which interact with the renin angiotensin aldosterone system (RAAS) were suspected to influence disease severity. METHODS AND RESULTS: We analyzed 1946 consecutive patients with cardiovascular comorbidities or hypertension enrolled in one of the largest European COVID-19 registries, the Lean European Open Survey on SARS-CoV-2 (LEOSS) registry. Here, we show that angiotensin II receptor blocker intake is associated with decreased mortality in patients with COVID-19 [OR 0.75 (95% CI 0,59-0.96; p = 0.013)]. This effect was mainly driven by patients, who presented in an early phase of COVID-19 at baseline [OR 0,64 (95% CI 0,43-0,96; p = 0.029)]. Kaplan-Meier analysis revealed a significantly lower incidence of death in patients on an angiotensin receptor blocker (ARB) (n = 33/318;10,4%) compared to patients using an angiotensin-converting enzyme inhibitor (ACEi) (n = 60/348;17,2%) or patients who received neither an ACE-inhibitor nor an ARB at baseline in the uncomplicated phase (n = 90/466; 19,3%; p<0.034). Patients taking an ARB were significantly less frequently reaching the mortality predicting threshold for leukocytes (p<0.001), neutrophils (p = 0.002) and the inflammatory markers CRP (p = 0.021), procalcitonin (p = 0.001) and IL-6 (p = 0.049). ACE2 expression levels in human lung samples were not altered in patients taking RAAS modulators. CONCLUSION: These data suggest a beneficial effect of ARBs on disease severity in patients with cardiovascular comorbidities and COVID-19, which is linked to dampened systemic inflammatory activity.

What about the others: differential diagnosis of COVID-19 in a German emergency department.

BACKGROUND: The ongoing COVID-19 pandemic remains a major challenge for worldwide health care systems and in particular emergency medicine. An early and safe triage in the emergency department (ED) is especially crucial for proper therapy. Clinical symptoms of COVID-19 comprise those of many common diseases; thus, differential diagnosis remains challenging. METHOD: We performed a retrospective study of 314 ED patients presenting with conceivable COVID-19 symptoms during the first wave in Germany. All were tested for COVID-19 with SARS-Cov-2-nasopharyngeal swabs. Forty-seven patients were positive. We analyzed the 267 COVID-19 negative patients for their main diagnosis and compared COVID-19 patients with COVID-19 negative respiratory infections for differences in laboratory parameters, symptoms, and vital signs. RESULTS: Among the 267 COVID-19 negative patients, 42.7% had respiratory, 14.2% had other infectious, and 11.2% had cardiovascular diseases. Further, 9.0% and 6.7% had oncological and gastroenterological diagnoses, respectively. Compared to COVID-19 negative airway infections, COVID-19 patients showed less dyspnea (OR 0.440; p = 0.024) but more dysgeusia (OR 7.631; p = 0.005). Their hospital stay was significantly longer (9.0 vs. 5.6 days; p = 0.014), and their mortality significantly higher (OR 3.979; p = 0.014). CONCLUSION: For many common ED diagnoses, COVID-19 should be considered a differential diagnosis. COVID-19 cannot be distinguished from COVID-19 negative respiratory infections by clinical signs, symptoms, or laboratory results. When hospitalization is necessary, the clinical course of COVID-19 airway infections seems to be more severe compared to other respiratory infections. TRIAL REGISTRATION: German Clinical Trial Registry DRKS, DRKS-ID of the study: DRKS00021675 date of registration: May 8th, 2020, retrospectively registered.

Long-Term SARS-CoV-2 Specific Immunity Is Affected by the Severity of Initial COVID-19 and Patient Age.

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is currently the greatest medical challenge. Although crucial to the future management of the pandemic, the factors affecting the persistence of long-term SARS-CoV-2 immunity are not well understood. Therefore, we determined the extent of important correlates of SARS-CoV-2 specific protection in 200 unvaccinated convalescents after COVID-19. To investigate the effective memory response against the virus, SARS-CoV-2 specific T cell and humoral immunity (including virus-neutralizing antibodies) was determined over a period of one to eleven months. SARS-CoV-2 specific immune responses were present in 90% of individual patients. Notably, immunosuppressed patients did not have long-term SARS-CoV-2 specific T cell immunity. In our cohort, the severity of the initial illness influenced SARS-CoV-2 specific T cell immune responses and patients' humoral immune responses to Spike (S) protein over the long-term, whereas the patients' age influenced Membrane (M) protein-specific T cell responses. Thus, our study not only demonstrated the long-term persistence of SARS-CoV-2 specific immunity, it also determined COVID-19 severity and patient age as significant factors affecting long-term immunity.

Pre-medication with oral anticoagulants is associated with better outcomes in a large multinational COVID-19 cohort with cardiovascular comorbidities.

AIMS: Coagulopathy and venous thromboembolism are common findings in coronavirus disease 2019 (COVID-19) and are associated with poor outcome. Timely initiation of anticoagulation after hospital admission was shown to be beneficial. In this study we aim to examine the association of pre-existing oral anticoagulation (OAC) with outcome among a cohort of SARS-CoV-2 infected patients. METHODS AND RESULTS: We analysed the data from the large multi-national Lean European Open Survey on SARS-CoV-2 infected patients (LEOSS) from March to August 2020. Patients with SARS-CoV-2 infection were eligible for inclusion. We retrospectively analysed the association of pre-existing OAC with all-cause mortality. Secondary outcome measures included COVID-19-related mortality, recovery and composite endpoints combining death and/or thrombotic event and death and/or bleeding event. We restricted bleeding events to intracerebral bleeding in this analysis to ensure clinical relevance and to limit reporting errors. A total of 1 433 SARS-CoV-2 infected patients were analysed, while 334 patients (23.3%) had an existing premedication with OAC and 1 099 patients (79.7%) had no OAC. After risk adjustment for comorbidities, pre-existing OAC showed a protective influence on the endpoint death (OR 0.62, P = 0.013) as well as the secondary endpoints COVID-19-related death (OR 0.64, P = 0.023) and non-recovery (OR 0.66, P = 0.014). The combined endpoint death or thrombotic event tended to be less frequent in patients on OAC (OR 0.71, P = 0.056). CONCLUSIONS: Pre-existing OAC is protective in COVID-19, irrespective of anticoagulation regime during hospital stay and independent of the stage and course of disease.

Prediction of COVID-19 deterioration in high-risk patients at diagnosis: an early warning score for advanced COVID-19 developed by machine learning.

PURPOSE: While more advanced COVID-19 necessitates medical interventions and hospitalization, patients with mild COVID-19 do not require this. Identifying patients at risk of progressing to advanced COVID-19 might guide treatment decisions, particularly for better prioritizing patients in need for hospitalization. METHODS: We developed a machine learning-based predictor for deriving a clinical score identifying patients with asymptomatic/mild COVID-19 at risk of progressing to advanced COVID-19. Clinical data from SARS-CoV-2 positive patients from the multicenter Lean European Open Survey on SARS-CoV-2 Infected Patients (LEOSS) were used for discovery (2020-03-16 to 2020-07-14) and validation (data from 2020-07-15 to 2021-02-16). RESULTS: The LEOSS dataset contains 473 baseline patient parameters measured at the first patient contact. After training the predictor model on a training dataset comprising 1233 patients, 20 of the 473 parameters were selected for the predictor model. From the predictor model, we delineated a composite predictive score (SACOV-19, Score for the prediction of an Advanced stage of COVID-19) with eleven variables. In the validation cohort (n = 2264 patients), we observed good prediction performance with an area under the curve (AUC) of 0.73 ± 0.01. Besides temperature, age, body mass index and smoking habit, variables indicating pulmonary involvement (respiration rate, oxygen saturation, dyspnea), inflammation (CRP, LDH, lymphocyte counts), and acute kidney injury at diagnosis were identified. For better interpretability, the predictor was translated into a web interface. CONCLUSION: We present a machine learning-based predictor model and a clinical score for identifying patients at risk of developing advanced COVID-19.