Lack of association between HLA and asymptomatic SARS-CoV-2 infection (preprint)

Human genetic studies of critical COVID-19 pneumonia have revealed the essential role of type I interferon-dependent innate immunity to SARS-CoV-2 infection. Conversely, an association between the HLA-B*15:01 allele and asymptomatic SARS-CoV-2 infection in unvaccinated individuals was recently reported, suggesting a contribution of pre-existing T cell-dependent adaptive immunity. We report a lack of association of classical HLA alleles, including HLA-B*15:01, with pre-omicron asymptomatic SARS-CoV-2 infection in unvaccinated participants in a prospective population-based study in the US (191 asymptomatic vs. 945 symptomatic COVID-19 cases). Moreover, we found no such association in the international COVID Human Genetic Effort cohort (206 asymptomatic vs. 574 mild or moderate COVID-19 cases and 1,625 severe or critical COVID-19 cases). Finally, in the Human Challenge Characterisation study, the three HLA-B*15:01 individuals infected with SARS-CoV-2 developed symptoms. As with other acute primary infections, no classical HLA alleles favoring an asymptomatic course of SARS-CoV-2 infection were identified. These findings suggest that memory T-cell immunity to seasonal coronaviruses does not strongly influence the outcome of SARS-CoV-2 infection in unvaccinated individuals.

Defective type I interferon immunity is associated with increasing COVID-19 severity (preprint)

Host immunity to infection with SARS-CoV-2 is highly variable, dictating diverse clinical outcomes ranging from asymptomatic to severe disease and death. We previously reported that reduced blood type I interferon (IFN-I) in severe COVID-19 patients preceded clinical worsening. These results were supported by studies which identified genetic mutations in loci of the TLR3- or TLR7-dependent IFN-I pathways, or autoantibodies neutralizing IFNα or IFNω, as major risk factors for development of severe and critical COVID-19 pneumonia. Here, we analyzed a range of IFN-I associated responses in patient cohorts with different severities of COVID-19, showing that baseline plasma IFNα measures differed significantly according to the immunoassay used, as well as timing of sampling, the IFNα subtype measured, and the presence of autoantibodies. We then compared immune responses induced by ex vivo stimulation between non-hospitalized moderate cases (n=27) and hospitalized (n=17) adult patients that required oxygen supplementation. This showed a consistently reduced induction of IFN-I proteins in hospitalized COVID-19 patients upon stimulation, that was not associated with detectable neutralizing autoantibodies against IFNα or IFNω. We confirmed the poor induction of IFN-I in an independent patient cohort (n=33), and showed it was more pronounced with severe disease. Intracellular proteomic analysis showed that while monocyte numbers were increased in hospitalized COVID-19 patients, they did not secrete IFN-I in response to stimulation. This was further confirmed by ex vivo whole blood stimulation with IFN-I which induced a transcriptomic response associated with inflammation in hospitalized COVID-19 patients, that was not seen in controls or non-hospitalized moderate cases. These results may explain the dichotomy of the poor clinical response to IFN-I based treatments in late stage COVID-19, despite the critical importance of IFN-I in early acute infection. An improved understanding of such variable responses to treatment may help to identify potential alternative therapeutic strategies.

Design, immunogenicity, and efficacy of a pan-sarbecovirus dendritic-cell targeting vaccine (preprint)

The emergence of SARS-CoV-2 variants of concern (VOCs) that escape pre-existing antibody neutralizing responses increases the need for vaccines that target conserved epitopes and induce cross-reactive B- and T-cell responses. We used a computational approach and sequence alignment analysis to design a new-generation subunit vaccine targeting conserved sarbecovirus B- and T-cell epitopes from Spike (S) and Nucleocapsid (N) to antigen-presenting cells expressing CD40 (CD40.CoV2). We demonstrate the potency of CD40.CoV2 to elicit high levels of cross-neutralizing antibodies against SARS-CoV-2, VOCs, and SARS-CoV-1 in K18-hACE2 transgenic mice, associated with improved viral control and survival after challenge. In addition, we demonstrate the potency of CD40.CoV2 in vitro to recall human multi-epitope, functional, and cytotoxic SARS-CoV-2 S- and N-specific T-cell responses that are unaffected by VOC mutations and cross-reactive with SARS-CoV-1 and, to a lesser extent, MERS epitopes. Overall, these findings provide a framework for a pan-sarbecovirus vaccine. Keywords: COVID-19, SARS-CoV-2, vaccine, pre-clinical model, sarbecoviruses

Cumulative Incidence of SARS-CoV-2 Infection and Associated Risk Factors Among Frontline Health Care Workers in Paris, France: The SEROCOV Prospective Cohort Study (preprint)

Objective: With the COVID-19 pandemic, documenting whether health care workers (HCWs) are at increased risk of SARS-CoV-2 contamination and identifying risk factors is of major concern. Methods In this multicenter prospective cohort study, HCWs from frontline departments were included in March and April 2020 and followed for 3 months. SARS-CoV-2 serology was performed at month 0 (M0), M1, and M3 and RT-PCR in case of symptoms. The primary outcome was laboratory-confirmed SARS-CoV-2 infection at M3. Risk factors of laboratory-confirmed SARS-CoV-2 infection at M3 were identified by multivariate logistic regression. Results Among 1,062 HCWs (median [interquartile range] age, 33 [28-42] years; 758 [71.4%] women; 321 [30.2%] physicians), the cumulative incidence of SARS-CoV-2 infection at M3 was 14.6% (95% confidence interval [CI] [12.5; 16.9]). Risk factors were the working department specialty, with increased risk for intensive care units (odds ratio 1.80, 95%CI [0.38; 8.58]), emergency departments (3.91 [0.83; 18.43]) and infectious diseases departments (4.22 [0.92; 18.28]); active smoking was associated with reduced risk (0.36 [0.21; 0.63]). Age, sex, professional category, number of years of experience in the job or department, and public transportation use were not significantly associated with laboratory-confirmed SARS-CoV-2 infection at M3. Conclusion The rate of SARS-CoV-2 infection in frontline HCWs was 14.6% at the end of the first COVID-19 wave in Paris and occurred mainly early. The study argues for an origin of professional in addition to private life contamination and therefore including HCWs in the first-line vaccination target population. It also highlights that smokers were at lower risk. Trial registration: The study has been registered on ClinicalTrials.gov: NCT04304690 first registered on 11/03/2020.

HGF and CXCL13, Two Antagonizing Cytokines in Lung Inflammation and Fibrosis, Predict the Severity and the Mortality of COVID-19 (preprint)

The objective of the present study was to identify biological signatures of severe COVID-19 predictive of admission in the intensive care unit (ICU). Over 170 immunological markers were investigated in a ‘discovery’ cohort (n=98 patients) of the Lausanne University Hospital (LUH-1). While cellular immunological markers lacked power in discriminating between ICU and non-ICU patients, 13 out of 49 cytokines were significantly associated with ICU admission in the three cohorts (P<0.05 to P<0.001). The cytokine results were confirmed in two ‘validation’ cohorts, i.e. the French COVID-19 Study (FCS; n=62) and a second LUH-2 cohort (n=47). Of note, HGF is a pleiotropic cytokine with anti-inflammatory properties playing a fundamental role in lung tissue repair, and CXCL13, a pro-inflammatory chemokine associated with pulmonary fibrosis and regulating the maturation of B cell response. The two cytokines in combination were the best predictors of ICU admission (positive and negative predictive values ranging from 81.8% to 93.1% and 85.2% to 94.4% in the 3 cohorts) and occurrence of death during patient follow-up (8.8 fold higher likelihood of death when both cytokines were increased). Up-regulation of HGF reflects the most powerful counter-regulatory mechanism of the host immune response to antagonize the pro-inflammatory cytokines including CXCL13 and to prevent lung fibrosis in COVID-19 patients.

Cumulative incidence of SARS-CoV-2 infection and associated risk factors among frontline health care workers in Paris, France: the SEROCOV prospective cohort study (preprint)

BackgroundWith the COVID-19 pandemic, documenting whether health care workers (HCWs) are at increased risk of SARS-CoV-2 contamination and identifying risk factors is of major concern. MethodsIn this multicenter prospective cohort study, HCWs from frontline departments were included in March and April 2020 and followed for 3 months. SARS-CoV-2 serology was performed at month 0 (M0), M1, and M3 and RT-PCR in case of symptoms. The primary outcome was laboratory-confirmed SARS-CoV-2 infection at M3. Risk factors of laboratory-confirmed SARS-CoV-2 infection at M3 were identified by multivariate logistic regression. ResultsAmong 1,062 HCWs (median [interquartile range] age, 33 [28-42] years; 758 [71.4%] women; 321 [30.2%] physicians), the cumulative incidence of SARS-CoV-2 infection at M3 was 14.6% (95% confidence interval [CI] [12.5; 16.9]). Risk factors were the working department specialty, with increased risk for intensive care units (odds ratio 1.80, 95%CI [0.38; 8.58]), emergency departments (3.91 [0.83; 18.43]) and infectious diseases departments (4.22 [0.92; 18.28]); active smoking was associated with reduced risk (0.36 [0.21; 0.63]). Age, sex, professional category, number of years of experience in the job or department, and public transportation use were not significantly associated with laboratory-confirmed SARS-CoV-2 infection at M3. ConclusionThe rate of SARS-CoV-2 infection in frontline HCWs was 14.6% at the end of the first COVID-19 wave in Paris and occurred mainly early. The study argues for an origin of professional in addition to private life contamination and therefore including HCWs in the first-line vaccination target population. It also highlights that smokers were at lower risk. Key messagesO_LIDuring the first epidemic wave, 14.6% of 1,062 first-line Health Care Workers had a positive serology and/or RT-PCR test for SARS-CoV-2. C_LIO_LIMost infections occurred early C_LIO_LIRisk was increased by working in infectious diseases (OR 4.22, 95% confidence interval [0.92; 18.28]), emergency (3.91 [0.83; 18.43]) and intensive care units (1.80, [0.38; 8.58]) C_LIO_LIBeing an active smoker was protective (0.36 [0.21; 0.3]). C_LI

Cumulative Incidence of SARS-CoV-2 Infection and Associated Risk Factors Among Frontline Health Care Workers in Paris, France: The SEROCOV Prospective Cohort Study (preprint)

Background: With the COVID-19 pandemic, documenting whether health care workers (HCWs) are at increased risk of SARS-CoV-2 contamination and identifying risk factors is of major concern.Methods: In this multicenter prospective cohort study, HCWs from COVID-19 frontline departments were included in March and April 2020 and followed for 3 months. SARS-CoV-2 serology was performed at month 0 (M0), M1, and M3 and RT-PCR in case of symptoms. The primary outcome was laboratory-confirmed SARS-CoV-2 infection (positive serology and/or positive RT-PCR result) at M3. Secondary outcomes were positive serology for SARS-CoV-2 at M0, M1 and M3. Risk factors of laboratory-confirmed SARS-CoV-2 infection at M3 were identified by multivariate logistic regression.Findings: Among 1,062 HCWs (median [interquartile range] age, 33 [28-42] years; 758 [71.4%] women; 321 [30.2%] physicians), the cumulative incidence of SARS-CoV-2 infection at M3 was 14.6% (95% confidence interval [CI] [12.5; 16.9]). Seroprevalence at M0, M1, and M3 was 5.9% [4.7; 7.5], 12.9% [10.9; 15.1] and 13.0% [11.1; 15.2], respectively. Risk factors were the working department specialty, with increased risk for intensive care units (odds ratio 1.80, 95%CI [0.38; 8.58]), emergency departments (3.91 [0.83; 18.43]) and infectious diseases departments (4.22 [0.92; 18.28]); active smoking was associated with reduced risk (0.36 [0.21; 0.63]). Age, sex, professional category, number of years of experience in the job or department, and public transportation use were not significantly associated with laboratory-confirmed SARS-CoV-2 infection at M3.Interpretation: The rate of SARS-CoV-2 infection in frontline HCWs was 14.6% at the end of the first COVID-19 wave in Paris and occurred mainly early. Seroprevalence in May was higher than in the general population. The study argues for an origin of professional in addition to private life contamination and therefore including HCWs in the first-line vaccination target population. It also highlights that smokers were at lower risk.Trial Registration: The study is registered on ClinicalTrials.gov: NCT04304690Funding Statement: The sponsor of the study was Assistance Publique-Hôpitaux de Paris (AP-HP), with study management by URC Pitié-Salpêtrière. This study was funded by the French Ministry of Health (Programme Hospitalier de Recherche Clinique) and the French Agency for Research (Fond d’amorçage de l’Agence National pour la Recherche).Declaration of Interests: None to declare. Ethics Approval Statement: The SEROCOV study was approved by the ethics committee (CPP Sud-Ouest et Outre-Mer I, approval no. 2-20-023 id7257) and all participants signed informed consent before inclusion.

Nasopharyngeal and serological anti SARS-CoV-2 IgG/IgA responses in COVID-19 patients. (preprint)

BackgroundThe systemic antibody responses to SARS-CoV-2 in COVID-19 patients has been extensively studied. However, much less is known about the mucosal responses in the upper airways at the site of initial SARS-CoV-2 replication. Local antibody responses in the nasopharyngeal epithelium, that are likely to determine the course of infection, have not been analysed so far nor their correlation with antibody responses in serum. MethodsThe IgG and IgA antibody responses were analysed in the plasma as well as in nasopharyngeal swabs (NPS) from the first four COVID-19 patients confirmed by RT-qPCR in France. Two were pauci-symptomatic while two developed severe disease. Taking advantage of a comprehensive series of plasma and nasopharyngeal samples, we characterized their antibody profiles from the second week post symptoms onset, by using an in-house ELISA to detect anti-SARS-CoV-2 Nucleoprotein (N) IgG and IgA. ResultsAnti-N IgG and IgA antibodies were detected in the NPS of severe patients. Overall, the levels of IgA and IgG antibodies in plasma and NPS appeared specific to each patient. ConclusionsAnti-N IgG and IgA antibodies are detected in NPS, and their levels are related to antibody levels in plasma. The two patients with severe disease exhibited different antibody profiles that may reflect different disease outcome. For the pauci-symptomatic patients, one showed a low anti-N IgG and IgA response in the plasma only, while the other one did not exhibit overt serological response.

Persistence of Sera Neutralizing Activity Six Month after Hospitalization for COVID-19 (preprint)

Background: SARS-CoV-2 induces a humoral response with seroconversion occurring within the first weeks after COVID-19 disease. Those antibodies exert a neutralizing activity against SARS-CoV-2, whose evolution overtime after COVID-19 is however unknown.Methods: In this monocentric prospective study, sera of 107 patients hospitalized with COVID-19 were collected at 3 months and 6 months post-infection. We performed quantitative neutralization experiments on top of high-throughput serological assays evaluating anti-Spike (S) and anti-Nucleocapsid (NP) IgG.Findings: Levels of sero-neutralization decreased significantly over study time, as well as IgG rates. After 6 months, 2.8% of the patients had a negative serological status for both anti-S and anti-NP IgG. However, all sera had a persistent and effective neutralizing effect on SARS-CoV-2 neutralizing assays. IgG levels correlated with sero-neutralization and this correlation was stronger for anti-S than for anti-NP antibodies. The level of sero-neutralization quantified at 6 months correlated with markers of initial severity, notably admission in intensive care units and the need for mechanical invasive ventilation.Interpretation: Decrease of IgG rates and serological assays becoming negative did not imply loss of neutralizing capacity in our patients. Those results are encouraging and in favor of sustained humoral response for at least 6 months in patients previously hospitalized for COVID-19, which will have to be considered in global deployment of vaccination strategy.Trial Registration: The French Covid cohort (NCT04262921)Funding Statement: The French COVID cohort is funding by the REACTing (REsearch & ACtion emergING infectious diseases) consortium and by a grant of the French Ministry of Health (PHRC n°20-0424).Outside the submitted work, JSH is supported by AP-HP, INSERM, the French National Research Agency (NADHeart ANR-17-CE17-0015-02, PACIFIC ANR-18-CE14-0032-01, CORRECT_LMNA ANR-19-CE17-0013-02), the ERA-Net-CVD (ANR-16-ECVD-0011-03, Clarify project), Fédération Française de Cardiologie, the Fondation pour la Recherche Médicale, and by a grant from the Leducq Foundation (18CVD05), and is coordinating a French PIA Project (2018-PSPC-07, PACIFIC-preserved, BPIFrance) and a University Research Federation against heart failure (FHU2019, PREVENT_Heart Failure). JG reports personal fees from ViiV Healthcare, Gilead Science, Janssen Cilag, and research grants from Gilead Sciences, MSD and ViiV Healthcare, outside the submitted work.Declaration of Interests: Authors have nothing to disclose. There are no relationships with industry.Ethics Approval Statement: The French Covid cohort (NCT04262921) is a prospective multi-center observational cohort sponsored by Inserm which was authorized by the French Ethics Committee CPP Ile-de-France VI (ID RCB:2020-A00256-33).

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.