Autoreactive T cells targeting type II pneumocyte antigens in COVID-19 convalescent patients.

BACKGROUND: The role of autoreactive T cells on the course of Coronavirus disease-19 (COVID-19) remains elusive. Type II pneumocytes represent the main target cells of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Autoimmune responses against antigens highly expressed in type II pneumocytes may influence the severity of COVID-19 disease. OBJECTIVE: The aim of this study was to investigate autoreactive T cell responses against self-antigens highly expressed in type II pneumocytes in the blood of COVID-19 patients with severe and non-severe disease. METHODS: We collected blood samples of COVID-19 patients with varying degrees of disease severity and of pre-pandemic controls. T cell stimulation assays with peptide pools of type II pneumocyte antigens were performed in two independent cohorts to analyze the autoimmune T cell responses in patients with non-severe and severe COVID-19 disease. Target cell lysis assays were performed with lung cancer cell lines to determine the extent of cell killing by type II PAA-specific T cells. RESULTS: We identified autoreactive T cell responses against four recently described self-antigens highly expressed in type II pneumocytes, known as surfactant protein A, surfactant protein B, surfactant protein C and napsin A, in the blood of COVID-19 patients. These antigens were termed type II pneumocyte-associated antigens (type II PAAs). We found that patients with non-severe COVID-19 disease showed a significantly higher frequency of type II PAA-specific autoreactive T cells in the blood when compared to severely ill patients. The presence of high frequencies of type II PAA-specific T cells in the blood of non-severe COVID-19 patients was independent of their age. We also found that napsin A-specific T cells from convalescent COVID-19 patients could kill lung cancer cells, demonstrating the functional and cytotoxic role of these T cells. CONCLUSIONS: Our data suggest that autoreactive type II PAA-specific T cells have a protective role in SARS-CoV-2 infections and the presence of high frequencies of these autoreactive T cells indicates effective viral control in COVID-19 patients. Type II-PAA-specific T cells may therefore promote the killing of infected type II pneumocytes and viral clearance.

The natural killer cell-associated rs9916629-C allele is a novel genetic risk factor for fatal COVID-19.

The severity of COVID-19 is associated with individual genetic host factors. Among these, genetic polymorphisms affecting natural killer (NK) cell responses, as variations in the HLA-E- (HLA-E*0101/0103), FcγRIIIa- (FcγRIIIa-158-F/V), and NKG2C- (KLRC2wt/del ) receptor, were associated with severe COVID-19. Recently, the rs9916629-C/T genetic polymorphism was identified that indirectly shape the human NK cell repertoire towards highly pro-inflammatory CD56bright NK cells. We investigated whether the rs9916629-C/T variants alone and in comparison to the other risk factors are associated with a fatal course of COVID-19. We included 1042 hospitalized surviving and 159 nonsurviving COVID-19 patients as well as 1000 healthy controls. rs9916629-C/T variants were genotyped by TaqMan assays and were compared between the groups. The patients' age, comorbidities, HLA-E*0101/0103, FcγRIIIa-158-F/V, and KLRC2wt/del variants were also determined. The presence of the rs9916629-C allele was a risk factor for severe and fatal COVID-19 (p < 0.0001), independent of the patients' age or comorbidities. Fatal COVID-19 was more frequent in younger patients (<69.85 years) carrying the FcγRIIIa-158-V/V (p < 0.006) and in older patients expressing the KLRC2del variant (p < 0.003). Thus, patients with the rs9916629-C allele have a significantly increased risk for fatal COVID-19 and identification of the genetic variants may be used as prognostic marker for hospitalized COVID-19 patients.

Tocilizumab vs. baricitinib in hospitalized severe COVID-19 patients: results from a real-world cohort.

BACKGROUND: Tocilizumab and baricitinib are recommended treatment options for hospitalized COVID-19 patients requiring oxygen support. Literature about its efficacy and safety in a head-to-head comparison is scarce. METHODS: Hospitalized COVID-19 patients requiring oxygen were treated with tocilizumab or baricitinib additionally to dexamethasone. Tocilizumab was available from February till the 19th of September 2021 and baricitinib from 21st of September. The primary outcome was in-hospital mortality. Secondary outcome parameters were progression to mechanical ventilation (MV), length-of-stay (LOS) and potential side effects. RESULTS: 159 patients (tocilizumab 68, baricitinib 91) with a mean age of 60.5 years, 64% male were included in the study. Tocilizumab patients were admitted 1 day earlier, were in a higher WHO category at the time of inclusion and had a higher CRP level on admission and treatment initiation. Patients receiving Tocilizumab were treated with remdesivir more often and only patients in the baricitinib group were treated with monoclonal antibodies. Other characteristics did not differ significantly. In-hospital mortality (18% vs. 11%, p = 0.229), progression to MV (19% vs. 11%, p = 0.173) and LOS (13 vs. 12 days, p = 0.114) did not differ between groups. Side effects were equally distributed between groups, except ALAT elevation which was significantly more often observed in the tocilizumab group (43% vs. 25%, p = 0.021). CONCLUSIONS: In-hospital mortality, progression to MV and LOS were not significantly different in patients treated with tocilizumab or baricitinib additionally to standard of care. Both drugs seem equally effective but further head-to-head trials are needed.

Evaluation of Five Commercial SARS-CoV-2 Antigen Tests in a Clinical Setting.

BACKGROUND: Point-of-care antigen tests (AgTs) for the detection of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) enable the rapid testing of infected individuals and are easy-to-use. However, there are few studies evaluating their clinical use. OBJECTIVE: The present study aimed to evaluate and compare the clinical performance characteristics of various commercial SARS-CoV-2 AgTs. DESIGN: The sensitivity of five AgTs, comprising four rapid antigen tests (RAT; AMP Rapid Test SARS-CoV-2 Ag, NADAL COVID-19 Antigen Rapid Test, CLINITEST Rapid COVID-19 Antigen Test, and Roche SARS-CoV-2 Rapid Antigen Test) and one sandwich chemiluminescence immunoassay (CLIA; LIAISON SARS-CoV-2 Assay), were evaluated in 300 nasopharyngeal (NP) swabs. Reverse transcriptase (RT) polymerase chain reaction (PCR) was used as a reference method. PARTICIPANTS: NP swabs were collected from patients admitted to hospital due to COVID-19. KEY RESULTS: Sensitivities of the AgTs ranged from 64.9 to 91.7% for samples with RT-PCR cycle threshold (Ct) values lower than 30 and were 100% for cycle threshold (Ct) values lower than 20. The highest sensitivity was observed for CLINITEST Rapid COVID-19 Antigen Test, and Roche SARS-CoV-2 rapid antigen test. Multivariate analysis using time from symptom onset and the Ct value for AgT sensitivity showed an inverse correlation. Further, the female sex was an independent factor of lower RAT sensitivity. CONCLUSIONS: Antigen tests from NP swab samples show high sensitivity in patients with a Ct value < 20. The best clinical sensitivity can be obtained using AgTs within the first 6 days after symptom onset.

Assessment of S1-, S2-, and NCP-Specific IgM, IgA, and IgG Antibody Kinetics in Acute SARS-CoV-2 Infection by a Microarray and Twelve Other Immunoassays.

In this study, we comprehensively analyzed multispecific antibody kinetics of different immunoglobulins in hospitalized patients with acute severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Three hundred fifty-four blood samples longitudinally obtained from 81 IgG-seroconverting progressed coronavirus disease 2019 (CoVID-19) patients were quantified for spike 1 (S1), S2, and nucleocapsid protein (NCP)-specific IgM, IgA, IgG, and total Ig antibodies using a microarray, 11 different enzyme-linked immunosorbent assays (ELISAs)/chemiluminescence immunoassays (CLIAs), and 1 rapid test by seven manufacturers. The assays' specificity was assessed in 130 non-CoVID-19 pneumonia patients. Using the microarray, NCP-specific IgA and IgG antibodies continuously displayed higher detection rates during acute CoVID-19 than S1- and S2-specific ones. S1-specific IgG antibodies, however, reached higher peak values. Until the 26th day post-symptom onset, all patients developed IgG responses against S1, S2, and NCP. Although detection rates by ELISAs/CLIAs generally resembled those of the microarray, corresponding to the target antigen, sensitivities and specificities varied among all tests. Notably, patients with more severe CoVID-19 displayed higher IgG and IgA levels, but this difference was mainly observed with S1-specific immunoassays. In patients with high SARS-CoV-2 levels in the lower respiratory tract, we observed high detection rates of IgG and total Ig immunoassays with a particular rise of S1-specific IgG antibodies when viral concentrations in the tracheal aspirate subsequently declined over time. In summary, our study demonstrates that differences in sensitivity among commercial immunoassays during acute SARS-CoV-2 infection are only partly related to the target antigen. Importantly, our data indicate that NCP-specific IgA and IgG antibodies are detected earlier, while higher S1-specific IgA antibody levels occur in severely ill patients.

Deletion of the NKG2C receptor encoding KLRC2 gene and HLA-E variants are risk factors for severe COVID-19.

PURPOSE: Host genetic variants may contribute to severity of COVID-19. NKG2C+ NK cells are potent antiviral effector cells, potentially limiting the extent of SARS-CoV-2 infections. NKG2C is an activating NK cell receptor encoded by the KLRC2 gene, which binds to HLA-E on infected cells leading to NK cell activation. Heterozygous or homozygous KLRC2 deletion (KLRC2del) may naturally occur and is associated with a significantly lower or absent NKG2C expression level. In addition, HLA-E*0101/0103 genetic variants occur, caused by a single-nucleotide polymorphism. We therefore investigated whether the severity of COVID-19 is associated with these genetic variants. METHODS: We investigated the distribution of KLRC2 deletion and HLA-E*0101/0103 allelic variants in a study cohort of 361 patients with either mild (N = 92) or severe (N = 269) COVID-19. RESULTS: Especially the KLRC2del, and at a lower degree the HLA-E*0101, allele were significantly overrepresented in hospitalized patients (p = 0.0006 and p = 0.01), particularly in patients requiring intensive care (p < 0.0001 and p = 0.01), compared with patients with mild symptoms. Both genetic variants were independent risk factors for severe COVID-19. CONCLUSION: Our data show that these genetic variants in the NKG2C/HLA-E axis have a significant impact on the development of severe SARS-CoV-2 infections, and may help to identify patients at high-risk for severe COVID-19.

Muscle involvement in SARS-CoV-2 infection.

BACKGROUND AND PURPOSE: Since the outbreak of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic, several reports indicated neurological involvement in COVID-19 disease. Muscle involvement has also been reported as evidenced by creatine kinase (CK) elevations and reports of myalgia. METHODS: Creatine kinase, markers of inflammation, pre-existing diseases and statin use were extracted from records of Austrian hospitalised COVID-19 patients. Disease severity was classified as severe in case of intensive care unit (ICU) admission or mortality. COVID-19 patients were additionally compared to an historical group of hospitalised influenza patients. RESULTS: Three hundred fifty-one patients with SARS-CoV-2 and 258 with influenza were included in the final analysis. CK was elevated in 27% of COVID-19 and in 28% of influenza patients. CK was higher in severe COVID-19 as were markers of inflammation. CK correlated significantly with inflammation markers, which had an independent impact on CK when adjusted for demographic variables and disease severity. Compared to influenza patients, COVID-19 patients were older, more frequently male, had more comorbidities, and more frequently had a severe disease course. Nevertheless, influenza patients had higher baseline CK than COVID-19, and 35.7% of intensive care unit (ICU)-admitted patients had CK levels >1,000 U/L compared to only 4.7% of ICU-admitted COVID-19 patients. CONCLUSIONS: HyperCKemia occurs in a similar frequency in COVID-19 and influenza infection. CK levels were lower in COVID-19 than in influenza in mild and severe disease. CK levels strongly correlate with disease severity and markers of inflammation. To date, it remains unclear whether hyperCKemia is due to a virus-triggered inflammatory response or direct muscle toxicity.

COVID-19 is not "just another flu": a real-life comparison of severe COVID-19 and influenza in hospitalized patients in Vienna, Austria.

BACKGROUND: COVID-19 is regularly compared to influenza. Mortality and case-fatality rates vary widely depending on incidence of COVID-19 and the testing policy in affected countries. To date, data comparing hospitalized patients with COVID-19 and influenza is scarce. METHODS: Data from patients with COVID-19 were compared to patients infected with influenza A (InfA) and B (InfB) virus during the 2017/18 and 2018/19 seasons. All patients were ≥ 18 years old, had PCR-confirmed infection and needed hospital treatment. Demographic data, medical history, length-of-stay (LOS), complications including in-hospital mortality were analyzed. RESULTS: In total, 142 patients with COVID-19 were compared to 266 patients with InfA and 300 with InfB. Differences in median age (COVID-19 70.5 years vs InfA 70 years and InfB 77 years, p < 0.001) and laboratory results were observed. COVID-19 patients had fewer comorbidities, but complications (respiratory insufficiency, pneumonia, acute kidney injury, acute heart failure and death) occurred more frequently. Median length-of-stay (LOS) was longer in COVID-19 patients (12 days vs InfA 7 days vs. InfB 7 days, p < 0.001). There was a fourfold higher in-hospital mortality in COVID-19 patients (23.2%) when compared with InfA (5.6%) or InfB (4.7%; p < 0.001). CONCLUSION: In hospitalized patients, COVID-19 is associated with longer LOS, a higher number of complications and higher in-hospital mortality compared to influenza, even in a population with fewer co-morbidities. This data, a high reproduction number and limited treatment options, alongside excess mortality during the SARS-CoV-2 pandemic, support the containment strategies implemented by most authorities.

Diagnosis of COVID-19 using multiple antibody assays in two cases with negative PCR results from nasopharyngeal swabs.

We report of two cases of progressed COVID-19 with negative PCR tests from nasopharyngeal swabs, in whom diagnosis was made by different antibody assays, including a lateral flow rapid test and multiple commercial ELISAs, finally confirmed by comprehensive serological assays. These cases highlight that commercial ELISAs and even rapid tests might significantly aid the diagnosis of COVID-19, particularly, if a combination of serological assays is used with a specific clinical question, in severely ill patients after seroconversion and when comprehensive serological methods are used for confirmation.

Performance of Severe Acute Respiratory Syndrome Coronavirus 2 Antibody Assays in Different Stages of Infection: Comparison of Commercial Enzyme-Linked Immunosorbent Assays and Rapid Tests.

We comparatively assessed sensitivities and specificities of 4 commercial enzyme-linked immunosorbent assays (ELISAs) and 2 rapid tests in 77 patients with polymerase chain reaction-confirmed severe acute respiratory syndrome coronavirus 2 infection, grouped by interval since symptom onset. Although test sensitivities were low (<40%) within the first 5 days after disease onset, immunoglobulin (Ig) M, IgA, and total antibody ELISAs increased in sensitivity to >80% between days 6 and 10 after symptom onset. The evaluated tests (including IgG and rapid tests) provided positive results in all patients at or after the 11th day after onset of disease. The specificities of the ELISAs were 83% (IgA), 98% (IgG), and 97% (IgM and total antibody).

SARS-CoV-2 infections in "less visible" hospital staff: The roles and safety of environmental services and allied health professionals.

BACKGROUND: During the early SARS-CoV-2 pandemic, all healthcare workers had specific and essential functions. However, environmental services (e.g., cleaning staff) and allied health professionals (e.g., physiotherapists) are often less recognised inpatient care. The aim of our study was to evaluate SARS-CoV-2-infection rates and describe risk factors relevant to workplace transmission and occupational safety amongst healthcare workers in COVID-19 hospitals before the introduction of SARS-CoV-2-specific vaccines. METHODS: This cross-sectional study (from May 2020 to March 2021, standardised WHO early-investigation protocol) is evaluating workplace or health-related data, COVID-19-patient proximity, personal protective equipment (PPE) use, and adherence to infection prevention and control (IPC) measures, anti-SARS-CoV-2-antibody status, and transmission pathways. RESULTS: Out of n = 221 HCW (n = 189 cleaning/service staff; n = 32 allied health professionals), n = 17 (7.7 %) were seropositive. While even SARS-CoV-2-naïve HCW reported SARS-CoV-2-related symptoms, airway symptoms, loss of smell or taste, and appetite were the most specific for a SARS-CoV-2-infection. Adherence to IPC (98.6 %) and recommended PPE use (98.2 %) were high and not associated with seropositivity. In 70.6 %, transmission occurred in private settings; in 23.5 %, at the workplace (by interaction with SARS-CoV-2-positive colleagues [17.6 %] or patient contact [5.9 %]), or remained unclear (one case). CONCLUSIONS: Infection rates were higher in all assessed 'less visible' healthcare-worker groups compared to the general population. Our data indicates that, while IPC measures and PPE may have contributed to the prevention of patient-to-healthcare-worker transmissions, infections were commonly acquired outside of work and transmitted between healthcare workers within the hospital. This finding emphasises the importance of ongoing education on transmission prevention and regular infection screenings at work.

Immunoglobulin G production in COVID-19 - associations with age, outcome, viral persistence, inflammation and pro-thrombotic markers.

Age represents the major risk factor for fatal disease outcome in coronavirus disease (COVID-19) due to age-related changes in immune responses. On the one hand lymphocyte counts continuously decline with advancing age, on the other hand somatic hyper-mutations of B-lymphocytes and levels of class-switched antibodies diminish, resulting in lower neutralizing antibody titers. To date the impact of age on immunoglobulin G (IgG) production in response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is unknown. Therefore, we investigated the impact of age on the onset of IgG production and its association with outcome, viral persistence, inflammatory and thrombotic markers in consecutive, hospitalized COVID-19 patients admitted to the Clinic Favoriten (Vienna, Austria) between April and October 2020 that fulfilled predefined inclusion criteria. Three different IgGs against SARS-CoV-2 (spike protein S1, nucleocapsid (NC), and the spike protein receptor binding domain (RBD)) were monitored in plasma of 97 patients upon admission and three times within the first week followed by weekly assessment during their entire hospital stay. We analyzed the association of clinical parameters including C-reactive protein (CRP), D-dimer levels and platelet count as well as viral persistence with the onset and concentration of different anti-SARS-CoV-2 specific IgGs. Our data demonstrate that in older individuals anti-SARS-CoV-2 IgG production increases earlier after symptom onset and that deceased patients have the highest amount of antibodies against SARS-CoV-2 whereas intensive care unit (ICU) survivors have the lowest titers. In addition, anti-SARS-CoV-2 IgG concentrations are not associated with curtailed viral infectivity, inflammatory or thrombotic markers, suggesting that not only serological memory but also other adaptive immune responses are involved in successful viral killing and protection against a severe COVID-19 infection.

A Multivariant Surrogate Neutralization Assay Identifies Variant-Specific Neutralizing Antibody Profiles in Primary SARS-CoV-2 Omicron Infection.

Primary infection with the Omicron variant of Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) can be serologically identified with distinct profiles of neutralizing antibodies (nAbs), as indicated by high titers against the Omicron variant and low titers against the ancestral wild-type (WT). Here, we evaluated whether a novel surrogate virus neutralization assay (sVNT) that simultaneously quantifies the binding inhibition of angiotensin-converting enzyme 2 (ACE2) to the proteins of the WT- and Omicron-specific receptor-binding domains (RBDs) can identify nAb profiles after primary Omicron infection with accuracy similar to that of variant-specific live-virus neutralization tests (NTs). Therefore, we comparatively tested 205 samples from individuals after primary infection with the Omicron variant and the WT, and vaccinated subjects with or without Omicron breakthrough infections. Indeed, variant-specific RBD-ACE2 binding inhibition levels significantly correlated with respective NT titers (p < 0.0001, Spearman's r = 0.92 and r = 0.80 for WT and Omicron, respectively). In addition, samples from individuals after primary Omicron infection were securely identified with the sVNT according to their distinctive nAb profiles (area under the curve = 0.99; sensitivity: 97.2%; specificity: 97.84%). Thus, when laborious live-virus NTs are not feasible, the novel sVNT we evaluated in this study may serve as an acceptable substitute for the serological identification of individuals with primary Omicron infection.

Renin-angiotensin system inhibitor discontinuation in COVID-19 did not modify systemic ACE2 in a randomized controlled trial.

Despite the similar clinical outcomes after renin-angiotensin system (RAS) inhibitor (RASi) continuation or withdrawal in COVID-19, the effects on angiotensin-converting enzyme 2 (ACE2) and RAS metabolites remain unclear. In a substudy of the randomized controlled Austrian Corona Virus Adaptive Clinical Trial (ACOVACT), patients with hypertension and COVID-19 were randomized 1:1 to either RASi continuation (n = 30) or switch to a non-RASi medication (n = 29). RAS metabolites were analyzed using a mixed linear regression model (n = 30). Time to a sustained clinical improvement was equal and ACE2 did not differ between the groups but increased over time in both. Overall ACE2 was higher with severe COVID-19. ACE-S and Ang II levels increased as expected with ACE inhibitor discontinuation. These data support the safety of RASi continuation in COVID-19, although RASi were frequently discontinued in our post hoc analysis. The study was not powered to draw definite conclusions on clinical outcomes using small sample sizes.

ELIMINATE: a PCR record-based macroelimination project for systematic recall of HCV-RNA-positive persons in Austria.

BACKGROUND AND AIMS: Micro-elimination projects targeted to specific hepatitis C virus (HCV) risk populations have been successful. Systematic identification of persons with HCV viremia, regardless of risk group, based on already available laboratory records may represent an effective macroelimination approach to achieve global HCV elimination. METHODS: Persons with a last positive HCV-RNA PCR result between 2008-2020 in the reference virology laboratories in eastern Austria were identified. First, (i) we described their demographic characteristics, (ii) we systematically recalled persons to the respective centers and (iii) started antiviral treatment if HCV-RNA viremia was confirmed, and (iv) recorded sustained virologic response (SVR). This interim report includes the preliminary results from 8 participating centers. RESULTS: During the study period 22,682 persons underwent HCV-RNA PCR testing, 11,216 (49.4%) were positive at any point in time, and 6006 (26.5%) showed detectable HCV-RNA at the last PCR test, suggesting ongoing HCV viremia. At the time of this interim report, 2546/6006 HCV-RNA PCR(+) persons were evaluated: 443/2546 (17.4%) had died, 852/2546 (33.5%) had invalid contact data, and 547/2546 (21.5%) had achieved SVR between data retrieval and recall. Contact could be established in 236/704 (33.5%) of the remaining target population with 97/236 (41.1%) presenting at the clinic for treatment evaluation. Ultimately, 71/236 (30.1%) started antiviral treatment and SVR was documented in 47/71 (66.2%). CONCLUSION: This ELIMINATE project based on systematic assessment of HCV-RNA PCR-records, identified 6006 persons with potential persisting HCV viremia. Invalid contact data and missed visits for treatment evaluation were the main barriers towards HCV elimination within this project. Importantly, many subjects with HCV viremia lost to follow-up were successfully linked to care and started antiviral treatment.

Occupational challenges of healthcare workers during the COVID-19 pandemic: a qualitative study.

OBJECTIVES: To address structural determinants and healthcare workers' (HCWs) physical, mental, emotional and professional challenges of working during the COVID-19 pandemic. DESIGN: Exploratory qualitative study with semistructured interviews. Collected data were analysed using thematic analysis. SETTING: This qualitative study was undertaken with HCWs who mainly worked in intensive care units in six non-profit hospitals in Vienna, Austria. Data were collected from June 2020 to January 2021. PARTICIPANTS: A total of 30 HCWs (13 medical doctors, 11 qualified nursing staff, 2 nurse assistants, 2 physiotherapists and 2 technical/cleaning staff) who were in direct and indirect contact with patients with COVID-19 were included. RESULTS: Three overall themes resulted as relevant: challenges due to lack of preparedness, structural conditions, and physical and mental health of HCWs. Lack of preparedness included delayed infection prevention and control (IPC) guidelines, shortages of personal protective equipment combined with staff shortages (especially of nursing staff) and overworked personnel. Physical and mental strains resulted from HCWs being overworked and working permanently on alert to face medical uncertainties and the critical conditions of patients. HCWs lacked recognition on multiple levels and dealt with stigma and avoidance behaviour of colleagues. CONCLUSION: To mitigate HCWs' occupational health risks and staff turnover, we propose context-specific recommendations. The number of available essential workers in care of patients with COVID-19, especially nursing staff, should be carefully planned and increased to avert chronic work overload. Timely training and education in IPC for all HCWs is important. Providing supportive supervision is as essential as appropriate recognition by higher level management and the public.

[Diagnosis and treatment of COVID-19 in intensive care units]. / Diagnostik und Therapie von COVID-19 auf der Intensivstation.

Treatment of coronavirus disease 2019 (COVID-19) is particularly challenging due to the rapid scientific advances and the often significant hypoxemia. Use of high-flow oxygen, noninvasive mask ventilation, and the technique of awake proning can sometimes avoid the need for intubation. Mechanical ventilation follows the principles of ventilation for acute respiratory distress syndrome (ARDS; lung protective ventilation) and is generally supplemented by consequent positioning therapy (with at least 16 h in prone position in multiple cycles). Antiviral therapy options such as remdesivir usually come too late for patients with COVID-19 in the ICU, the only exception being the administration of monoclonal antibodies for patients without seroconversion. The value of immunomodulatory therapy such as dexamethasone is undisputed. Interleukin­6 antagonists, on the other hand, are rather problematic for ICU patients, and for Janus kinase inhibitors, data and experience are still insufficient in this context.

Rapid Detection of Bacterial and Fungal Pathogens Using the T2MR versus Blood Culture in Patients with Severe COVID-19.

A high rate of bacterial and fungal superinfections was reported in critically ill patients with COVID-19. However, diagnosis can be challenging. The aim of this study is to evaluate the sensitivity and the clinical utility of the point-of-care method T2 magnetic resonance (T2MR) with the gold standard: the blood culture. T2MR can potentially detect five different Candida species and six common bacteria (so-called "ESKAPE" pathogens including Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Acinet`obacter baumanii, Pseudomonas aeruginosa, and Enterococcus faecium). If superinfection was suspected in patients with COVID-19 admitted to the intensive care unit, blood culture and two panels of T2MR were performed. Eighty-five diagnostic bundles were performed in 60 patients in total. T2MR detected an ESKAPE pathogen in 9 out of 85 (10.6%) samples, compared to BC in 3 out of 85 (3.5%). A Candida species was detected in 7 of 85 (8.2%) samples of T2MR compared to 1 out of 85(1.2%) in blood culture. The mean time to positive test result in samples with concordant positive results was 4.5 h with T2MR and 52.5 h with blood culture. The additional use of T2MR enables a highly sensitive and rapid detection of ESKAPE and Candida pathogens. IMPORTANCE Coronavirus disease 2019 (COVID-19) has led to a high number of deaths since the beginning of the pandemic worldwide. One of the reasons is the high number of bacterial and fungal superinfections in patients suffering from critical disease. However, diagnosis is often challenging. In this study we could show that the additional use of the culture-independent method T2MR did not only show a much higher detection rate of bacterial and fungal pathogens but also a significantly shorter time until detection and therapy change compared to the gold standard: the blood culture. The implementation of T2MRin the care of patients with severe course of COVID-19 might lead to an earlier sufficient antimicrobial therapy and as a result lower mortality and less use of broad-spectrum unnecessary therapy reducing the risk of resistance development.

Heterogeneous SARS-CoV-2-Neutralizing Activities After Infection and Vaccination.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) with different resistance levels to existing immunity have recently emerged. Antibodies that recognize the SARS-CoV-2 spike (S) protein and exhibit neutralizing activities are considered the best correlate of protection and an understanding of humoral immunity is crucial for controlling the pandemic. We thus analyzed such antibodies in individuals recovered from infection in 2020 as well as vaccinees after two doses of an mRNA vaccine. Methods: Neutralizing antibody responses against three SARS-CoV-2 variants (D614G, VOCs Beta and Delta) were determined in serum samples from 54 infected individuals (24 non-hospitalized, 30 hospitalized) and 34 vaccinees shortly after symptom onset or second vaccination, respectively, as well as six months later. In addition, the effect of the S sequence of the infecting strain on neutralization was studied. Results: Non-hospitalized patients had the lowest neutralization titers against all variants, while those of hospitalized patients equaled or exceeded those of vaccinees. Neutralizing activity was lower against the two VOCs and declined significantly in all cohorts after six months. This decrease was more pronounced in hospitalized and vaccinated individuals than in non-hospitalized patients. Of note, the specific neutralizing activity (NT titer/ELISA value ratio) was higher in the infected cohorts than in vaccinees and did not differ between non-hospitalized and hospitalized patients. Patients infected with viral strains carrying mutations in the N-terminal domain of the spike protein were impaired in Beta VOC neutralization. Conclusions: Specific neutralizing activities were higher in infected than in vaccinated individuals, and no difference in the quality of these antibodies was observed between hospitalized and non-hospitalized patients, despite significantly lower titers in the latter group. Additionally, antibody responses of infected individuals showed greater heterogeneity than those of vaccinees, which was associated with mutations in the spike protein of the infecting strain. Overall, our findings yielded novel insights into SARS-CoV-2-specific neutralizing antibodies, evolving differently after virus infection and COVID-19 vaccination, which is an important issue to consider in ongoing vaccine strategy improvements.