‘Which severe COVID-19 patients could benefit from High dose dexamethasone? A Bayesian reanalysis of a randomized clinical trial (preprint)

Background: The respective benefits of high and low doses of dexamethasone (DXM) in patients with severe acute respiratory syndrome coronavirus 2 (SARS-Cov2) and acute respiratory failure (ARF) are controversial, with two large triple-blind RCTs reaching opposite conclusions. In the COVIDICUS trial, we argued against any additional benefit of high-dose dexamethasone (DXM20). We aimed to explore whether some specific patient phenotypes could benefit from DXM20 compared to the standard of care dose of DXM (DXMSoC). Methods: We performed a post hoc exploratory Bayesian analysis of 473 patients who received either DXM6 or DXM20 in the COVIDICUS trial. The primary outcome was the 60-day mortality rate of DXM20 over DXMSoC, with the treatment effect measured on the posterior mean of relative risk (RR) estimated using a beta-binomial model with 95% credibility intervals (95% CrI). Bayesian measures of interaction quantified the probability of interaction (Pr Interact) that the RR of 60-day death differed across the subsets by 20%. Results: Overall, the posterior mean RR of Day 60 mortality was 1.06 with a 95% credible confidence interval (0.77 to 1.44) and a posterior probability of benefit and harm of 27.0% and 50.5%, respectively. There was some evidence of treatment by subset interaction according to age, with the benefit increasing in patients aged below 70 years (RR=0.74, 95% CrI 0.41-1.22) compared to those aged above 70 (RR=1.12, 95% CrI 0.77 to 1.60) (Pr Interact, 77%), when the time since symptoms onset was lower than 7 days (RR=0.66, 95% CrI 0. 36 to 1.09) compared to 7 days or more (RR=1.15, 95% CrI 0.76 to 1.67) (Pr Interact, 90%) and in patients receiving remdesivir (RR=0.62, 95% CrI 0.29 to 1.14) compared to those who did not (RR=1.12, 95% CrI 0.78 to 1.58) (Pr Interact, 88%). Conclusions: In this exploratory post hoc Bayesian analysis, compared with standard-of-care DXM, high-dose DXM may benefit patients aged less than 70 years with severe ARF that occurred less than 7 days after symptoms onset. The use of remdesivir may also favour the benefit of DXM20. Further analysis is needed to confirm these findings. Trial registration: NCT04344730, date of registration April 14, 2020 (https://clinicaltrials.gov/ct2/show/NCT04344730?term=NCT04344730&draw=2&rank=1); EudraCT: 2020-001457-43 (https://www.clinicaltrialsregister.eu/ctr-search/search?query=2020-001457-43).

Clinical phenotypes and outcomes associated with SARS-CoV-2 variant Omicron, sublineages BA.1, BA.1.1, BA.2 and impact of mutational patterns in critically ill French patients with COVID-19 (preprint)

Infection with SARS-CoV-2 variant Omicron is considered to be less severe than infection with variant Delta, with a rarer occurrence of severe disease requiring intensive care. However, a substantial number of patients infected with variant Omicron still experienced severe COVID-19. Little information is available on comorbid factors, clinical conditions and specific viral mutational patterns associated with the severity of variant Omicron infection. In this multicenter prospective cohort study, patients consecutively admitted for severe COVID-19 in 20 participating intensive care units in France between December 7th 2021 and May 1st 2022 were included. Among 259 patients for whom SARS-CoV-2 variant lineage was determined, we show that the clinical phenotype of patients infected with variant Omicron (n = 148) was different from that in those infected with variant Delta (n = 111). We observed no significant relationship between Delta and Omicron variant lineages/sublineages and 28-day mortality (adjusted odds ratio [95% confidence interval] = 0.68 [0.35–1.32]; p = 0.253). Among Omicron-infected patients, 43.2% were immunocompromised, most of whom had received two doses of vaccine or more (85.9%) but displayed a poor humoral response to vaccination (mean difference in serum anti-spike IgG antibody titers between vaccinated and non-vaccinated immunocompromised patients: 1078 BAU/mL [-319.4; 2475.0]; p = 0.160). The mortality rate of immunocompromised patients infected with variant Omicron was significantly higher than that of non-immunocompromised patients (46.9% vs 26.2%; p = 0.009). In patients infected with variant Omicron, there was no association between specific sublineages (BA.1/BA.1.1 (n = 109) and BA.2 (n = 21)) or any viral genome polymorphisms or mutational profile and the 28-day mortality.

Could faecal viral excretion explain gastrointestinal symptoms in COVID-19 patients: co- infection involvement? (preprint)

Objectives: Physiopathological mechanisms responsible for digestive symptoms during COVID-19 are still unclear. The aim of this study was to determine the influence of faecal viral shedding on digestive symptoms and propose differential diagnoses to better understand the gastrointestinal clinical spectrum during acute COVID-19.Methods: Patients were included if one stool sample was available for microbiological investigation. Microbiological analysis consisted of syndromic PCR screening, and parasitological investigation included microsporidia and multiplex protozoa PCR. SARS-CoV-2 infection was diagnosed by viral detection (on respiratory samples and frozen stool samples) and by serology when necessary. Collected epidemiological, clinical, radiological, biological data and clinical course were compared according to COVID-19 status, faecal SARS-CoV-2 shedding and co-infection status.Results: 50 COVID+ and 67 COVID- patients were included. Faecal viral shedding was detected in 50% of stool samples and was associated with higher viral load in the upper respiratory tract. There was no difference in the proportion of detected enteric pathogens between COVID-19 status. No impact was observed on clinical course regardless of COVID-19 status, faecal SARS-CoV-2 shedding and coinfection status.Conclusions: SARS-CoV-2 shedding and enteric pathogen involvement in gastrointestinal presentation is still unclear. However, differential diagnostic investigation revealed frequently occurring common enteric pathogens in COVID-19 patients.

Monitoring and forecasting the SARS-Covid-19 pandemic in France (preprint)

Over the past year, many countries have resorted multiple times to drastic social restrictions to prevent saturation of their health care system, and to regain control over an otherwise exponentially increasing SARS-Covid-19 pandemic evolution. With the advent of data-sharing, computational approaches have gained a key role in evaluating future scenarios and offering predictions in a constantly evolving social environment. To design optimal social, hospitalization and economical strategies that guarantee control over the pandemic progression, we developed a data-driven modelling framework with the aim to provide reliable near future predictions under constantly evolving social and pandemic events. The framework is flexible enough to be used at a single hospital, regional or national level. We used a variety of data such as social, serological, testing and clinical data to compute the infection dynamics and the hospital workload for France. We developed inference methods to calibrate model parameters from observed hospitalization statistics over adjustable time periods. We applied our model to study the age stratified pandemic evolution inside and outside hospitals until February 2021, and the competition between vaccinations and the novel delta variant. We obtained several predictions about hidden pandemic properties such as fractions of infected, infection hospitality and infection fatality ratios. We show that reproduction numbers and herd immunity levels are not universal but strongly depend on the underlying social dynamics. We find that with normal social interactions the present vaccination status and rate is not sufficient to prevent a new pandemic wave driven by the delta variant.

Innate immune deficiencies in patients with COVID-19 (preprint)

COVID-19 can cause acute respiratory distress syndrome (ARDS), leading to death in a significant number of individuals. Evidence of a strong role of the innate immune system is accumulating, but the precise cells and mechanism involved remain unclear. In this study, we investigated the links between circulating innate phagocyte phenotype and functions and severity in COVID-19 patients. Eighty-four consecutive patients were included, 44 of which were in intensive care units (ICU). We performed an in-depth phenotyping of neutrophil and monocyte subpopulations and measured soluble activation markers in plasma. Additionally, myeloid cell functions (phagocytosis, oxidative burst, and NETosis) were evaluated on fresh cells from patients. Resulting parameters were linked to disease severity and prognosis. Both ICU and non-ICU patients had circulating neutrophils and monocytes with an activated phenotype, as well as elevated concentrations of soluble activation markers (calprotectin, myeloperoxidase, neutrophil extracellular traps, MMP9, sCD14) in their plasma. ICU patients were characterized by increased CD10low CD13low immature neutrophils, LOX-1+ and CCR5+ immunosuppressive neutrophils, and HLA-DRlow CD14low downregulated monocytes. Markers of immature and immunosuppressive neutrophils were strongly associated with severity and poor outcome. Moreover, neutrophils and monocytes of ICU patients had impaired antimicrobial functions, which correlated with organ dysfunction, severe infections, and mortality. Our study reveals a marked dysregulation of innate immunity in COVID-19 patients, which was correlated with severity and prognosis. Together, our results strongly argue in favor of a pivotal role of innate immunity in COVID-19 severe infections and pleads for targeted therapeutic options. One Sentence SummaryOur study reveals a marked dysregulation of innate immunity in COVID-19 patients, which correlates with severity and prognosis.

Impact of Early Corticosteroids on 60-day Mortality in Critically Ill Patients with COVID-19: A Multicenter Cohort Study of the OUTCOMEREA Network (preprint)

ObjectivesIn severe COVID-19 pneumonia, the appropriate timing and dosing of corticosteroids(CS) is not known. Patient subgroups for which CS could be more beneficial also need appraisal. The aim of this study was to assess the effect of early CS in COVID-19 pneumonia patients admitted to the ICU on the occurrence of 60-day mortality, ICU-acquired-bloodstream infections(ICU-BSI), and hospital-acquired pneumonia and ventilator-associated pneumonia(HAP-VAP).MethodsWe included patients with COVID-19 pneumonia admitted to 11 ICUs belonging to the French OutcomeReaTM network from January to May 2020. We used survival models with ponderation with inverse probability of treatment weighting (IPTW). Inflammation was defined as Ferritin >1000 µg/l or D-Dimers >1000 µg/l or C-Reactive Protein >100 mg/dL.ResultsThe study population comprised 302 patients having a median age of 61.6(53-70) years of whom 78.8% were male and 58.6% had at least one comorbidity. The median SAPS II was 33(25-44). Invasive mechanical ventilation was required in 34.8% of the patients. Sixty-six (21.8%) patients were in the Early-CS-subgroup. Most of them (n=55, 83.3%) received high doses of steroids. Overall, 60-day mortality was 29.4%. The risks of 60-day mortality (IPTWHR =0.88;95% CI 0.55 to 1.39, p=0.58), ICU-BSI and HAP-VAP were similar in the two groups. Importantly, early CS treatment was associated with a lower mortality rate in patients aged 60 years or more (IPTWHR, 0.51;95% CI, 0.29 – 0.91; p=0.02). But, CS was associated with an increased risk of death for the patients younger than 60 years without inflammation on admission (IPTWHR =8.17;95% CI, 1.76, 37.85; p=0.01).ConclusionFor patients with COVID-19 pneumonia, early CS treatment was not associated with patient survival. Interestingly, inflammation and age can significantly influence the effect of CS.

Remdesivir as a tool to relieve hospital care systems stressed by COVID-19: A modelling study on bed resources and budget impact (preprint)

Remdesivir and dexamethasone are the only drugs providing reductions in the lengths of hospital stays for COVID-19 patients. We assessed the impacts of remdesivir on hospital-bed resources and budgets affected by the COVID-19 outbreak. A stochastic agent-based model was combined with epidemiological data available on the COVID-19 outbreak in France and data from two randomized control trials. Strategies involving treating with remdesivir only patients with low-flow oxygen and patients with low-flow and high-flow oxygen were examined. Treating all eligible low-flow oxygen patients during the entirety of the second wave would have decreased hospital-bed occupancy in conventional wards by 4% [2%; 7%] and intensive care unit (ICU)-bed occupancy by 9% [6%; 13%]. Extending remdesivir use to high-flow-oxygen patients would have amplified reductions in ICU-bed occupancy by up to 14% [18%; 11%]. A minimum remdesivir uptake of 20% was required to observe decreases in bed occupancy. Dexamethasone had effects of similar amplitude. Depending on the treatment strategy, using remdesivir would, in most cases, generate savings (up to 722€) or at least be cost neutral (an extra cost of 34€). Treating eligible patients could significantly limit the saturation of hospital capacities, particularly in ICUs. The generated savings would exceed the costs of medications.

Viral epidemiology and SARS-CoV-2 coinfections with other respiratory viruses during the first COVID-19 wave in Paris, France (preprint)

Abstract: Objectives: Our work assessed the prevalence of co-infections in patients with SARS-CoV-2. Methods: All patients hospitalized in a Parisian hospital during the first wave of COVID-19 were tested by mPCR if they presented ILI symptoms. Results: A total of 806 patients (21%) were positive for SARS-CoV-2, 755 (20%) were positive for other respiratory viruses. Among the SARS-CoV-2 positive patients, 49 (6%) had viral co-infections. They presented similar age, symptoms, except for fever (p=0.013) and headaches (p=0.048), than single SARS-CoV-2 infections. Conclusions: SARS-CoV-2 infected patients presenting viral co-infections had similar clinical characteristics and prognosis than patients solely infected with SARS-CoV-2.

Two original observations concerning bacterial infections in COVID-19 patients hospitalized in intensive care units during the first wave of the epidemic in France (preprint)

Among 197 COVID-19 patients hospitalized in ICU, 88 (44.7%) experienced at least one bacterial infection, with pneumonia (39.1%) and bloodstream infections (15,7%) being the most frequent. Unusual findings include frequent suspicion of bacterial translocations originating from the digestive tract as well as bacterial persistence in the lungs despite adequate therapy.

Modeling of aerosol transmission of airborne pathogens in ICU rooms of COVID-19 patients with acute respiratory failure (preprint)

The COVID-19 pandemic has generated many concerns about cross-contamination risks, particularly in hospital settings and Intensive Care Units (ICU). Virus-laden aerosols produced by infected patients can propagate throughout ventilated rooms and put medical personnel entering them at risk. Experimental results found with a schlieren optical method have shown that the air flows generated by a cough and normal breathing were modified by the oxygenation technique used, especially when using High Flow Nasal Canulae, increasing the shedding of potentially infectious airborne particles. This study also uses a 3D Computational Fluid Dynamics model based on a Lattice Boltzmann Method to simulate the air flows as well as the movement of numerous airborne particles produced by a patients cough within an ICU room under negative pressure. The effects of different mitigation scenarii on the amount of aerosols potentially containing SARS-CoV-2 that are extracted through the ventilation system are investigated. Numerical results indicate that adequate bed orientation and additional air treatment unit positioning can increase by 40% the number of particles extracted and decrease by 25% the amount of particles deposited on surfaces 45s after shedding. This approach could help lay the grounds for a more comprehensive way to tackle contamination risks in hospitals, as the model can be seen as a proof of concept and be adapted to any room configuration.

CD177, a specific marker of neutrophil activation, is a hallmark of COVID-19 severity and death (preprint)

COVID-19 SARS-CoV-2 infection exhibits wide inter-individual clinical variability, from silent infection to severe disease and death. The identification of high-risk patients is a continuing challenge in routine care. We aimed to identify factors that influence clinical worsening. We analyzed 52 cell populations, 71 analytes, and RNA-seq gene expression in the blood of severe patients from the French COVID cohort upon hospitalization (n = 61). COVID-19 patients showed severe abnormalities of 27 cell populations relative to healthy donors (HDs). Forty-two cytokines, neutrophil chemo-attractants, and inflammatory components were elevated in COVID-19 patients. Supervised gene expression analyses showed differential expression of genes for neutrophil activation, interferon signaling, T- and B-cell receptors, EIF2 signaling, and ICOS-ICOSL pathways in COVID-19 patients. Unsupervised analysis confirmed the prominent role of neutrophil activation, with a high abundance of CD177, a specific neutrophil activation marker. CD177 was the most highly differentially-expressed gene contributing to the clustering of severe patients and its abundance correlated with CD177 protein serum levels. CD177 levels were higher in COVID-19 patients from both the French and "confirmatory" Swiss cohort (n = 203) than in HDs (P< 0.01) and in ICU than non-ICU patients (P< 0.001), correlating with the time to symptoms onset (P = 0.002). Longitudinal measurements showed sustained levels of serum CD177 to discriminate between patients with the worst prognosis, leading to death, and those who recovered (P = 0.01). These results highlight neutrophil activation as a hallmark of severe disease and CD177 assessment as a reliable prognostic marker for routine care.

SARS-CoV-2 N-antigenemia: A new alternative to nucleic acid amplification techniques (preprint)

Background. Molecular assays on nasopharyngeal swabs remain the cornerstone of COVID-19 diagnostic. Despite massive worldwide efforts, the high technicalities of nasopharyngeal sampling and molecular assays, as well as scarce resources of reagents, limit our testing capabilities. Several strategies failed, to date, to fully alleviate this testing process (e.g. saliva sampling or antigen testing on nasopharyngeal samples). We assessed the performances of a new ELISA microplate assay quantifying SARS-CoV-2 nucleocapsid antigen (N-antigen) in serum or plasma. Methods. The specificity of the assay, determined on 63 non-COVID patients, was 98.4% (95% confidence interval [CI], 85.3 to 100). Performances were determined on 227 serum samples from 165 patients with RT-PCR confirmed SARS-CoV-2 infection included in the French COVID and CoV-CONTACT cohorts. Findings. Sensitivity was 132/142, 93.0% (95% CI, 84.7 to 100), within the first two weeks after symptoms onset. A subset of 73 COVID-19 patients had a serum collected within 24 hours following or preceding a positive nasopharyngeal swab. Among patients with high nasopharyngeal viral loads, Ct value below 30 and 33, only 1/50 and 4/67 tested negative for N-antigenemia, respectively. Among patients with a negative nasopharyngeal RT-PCR, 8/12 presented positive N-antigenemia. The lower respiratory tract was explored for 6/8 patients, showing positive PCR in 5 cases. Interpretation. This is the first demonstration of the N-antigen antigenemia during COVID-19. Its detection presented a robust sensitivity, especially within the first 14 days after symptoms onset and high nasopharyngeal viral loads. These findings have to be confirmed with higher representation of outpatients. This approach could provide a valuable new option for COVID-19 diagnosis, only requiring a blood draw and easily scalable in all clinical laboratories.

Outcome of SARS-CoV-2 infection linked to MAIT cell activation and cytotoxicity: evidence for an IL-18 dependent mechanism (preprint)

Immune system dysfunction is paramount in Coronavirus disease 2019 (COVID-19) severity and fatality rate. Mucosal-Associated Invariant T (MAIT) cells are innate-like T cells involved in mucosal immunity and protection against viral infections. Here, we studied the immune cell landscape, with emphasis on MAIT cells, in a cohort of 182 patients including patients at various stages of disease activity. A profound decrease of MAIT cell counts in blood of critically ill patients was observed. These cells showed a strongly activated and cytotoxic phenotype that positively correlated with circulating pro-inflammatory cytokines, notably IL-18. MAIT cell alterations markedly correlated with disease severity and patient mortality. SARS-CoV-2-infected macrophages activated MAIT cells in a cytokine-dependent manner involving an IFN-dependent early phase and an IL-18-induced later phase. Therefore, altered MAIT cell phenotypes represent valuable biomarkers of disease severity and their therapeutic manipulation might prevent the inflammatory phase involved in COVID-19 aggravation.

Immune alterations during SARS-CoV-2-related acute respiratory distress syndrome (preprint)

We report a longitudinal analysis of the immune response associated with a fatal case of COVID-19. This patient exhibited a rapid evolution towards multiorgan failure. SARS-CoV-2 was detected in multiple nasopharyngeal, blood, and pleural samples, despite antiviral and immunomodulator treatment. Clinical evolution in the blood was marked by an increase (2-3 fold) in differentiated effector T cells expressing exhaustion (PD-1) and senescence (CD57) markers, an expansion of antibody-secreting cells, a 15-fold increase in {gamma}{delta} T-cell and proliferating NK-cell populations, and the total disappearance of monocytes, suggesting lung trafficking. In the serum, waves of a proinflammatory cytokine storm, Th1 and Th2 activation, and markers of T-cell exhaustion, apoptosis, cell cytotoxicity, and endothelial activation were observed until the fatal outcome. This case underscores the need for well-designed studies to investigate complementary approaches to control viral replication, the source of the hyperinflammatory status, and immunomodulation to target the pathophysiological response.