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ObjectiveTo investigate SARS-COV-2 viral clearance and viral load kinetics in the course of infection in children aged 1-6 years in comparison with adults. MethodsProspective cohort study of infected daycare children and staff and their close contacts in households from 11/2020-06/2021, comprising serial (self) sampling of upper respiratory tract specimen and testing for SARS-CoV-2 via PCR. Data on symptoms and exposure were used to determine the date of probable infection for each participant. We determined (a) viral clearance, and (b) viral load dynamics over time. Samples were taken from day 4-6 to day 16-18 after diagnosis of the index case in the respective daycare group (5 samples per participant). ResultsWe included 40 children (1-6 years) and 67 adults (18-77 years) with SARS-CoV-2 infection. Samples were available at a mean of 4.3 points of time per participant. Among the participants, the 12-day study period fell in different periods within the individual course of infection, ranging from day 5-17 to day 15-26 after assumed infection. Children reached viral clearance at a median of 20 days after assumed infection (95% CI 17-21 days, Kaplan Meier Analysis), adults at 23 days (95% CI 20-25 days, difference not significant). In both children and adults, viral load decreased over time with trajectories of the mean viral load not being statistically different between groups. Only small proportions of those tested positive had a viral load of >1 million copies/ml, which is considered the threshold for infectivity. Kaplan-Meier calculations show that from day 15 (95% CI 13-15), 50% of all participants that had a viral load no longer infectious or were negative. ConclusionChildren aged 1-6 and adults infected with SARS-CoV-2 (wild type and Alpha variant) did not differ significantly in terms of viral load kinetics and time needed to clear the virus. Therefore, containment measures are important also in the daycare settings as long as the pandemic continues.
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We included 852 patients in a prospectively recruiting multicenter matched case-control study in Germany to assess vaccine effectiveness (VE) in preventing COVID-19-associated hospitalization (Delta-variant dominance). Two-dose VE was 89% (95%CI 84-93%) overall, 79% in patients with >2 comorbidities and 77% in adults aged 60-75 years. A third dose increased VE to >93% in all patient-subgroups.
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SARS-CoV-2 mRNA vaccination of healthy individuals is highly immunogenic and protective against severe COVID-19. However, there are limited data on how disease-modifying therapies (DMTs) alter SARS-CoV-2 mRNA vaccine immunogenicity in patients with autoimmune diseases. Here we investigated the induction and stability of vaccine-specific antibodies, B cells, and T cells in multiple sclerosis (MS) patients on different DMTs in a prospective cohort study up to 6 months after homologous prime-boost mRNA vaccination. We analysed 103 MS patients of which 86 received anti-CD20-based B cell depletion (aCD20-BCD), fingolimod, interferon-{beta}, dimethyl fumarate, glatiramer acetate, teriflunomide or natalizumab, and compared them to 17 untreated MS patients. In contrast to all other DMTs and untreated patients, treatment with aCD20-BCD or fingolimod significantly reduced anti-S1 IgG, serum neutralizing activity, and RBD- and S2-specific B cells. MS patients receiving fingolimod additionally lacked S1- and S2-reactive CD4+ T cell responses. The duration of fingolimod treatment, rather than peripheral blood B and T cell counts prior to vaccination, determined whether patients successfully developed humoral immune responses. Fingolimod blocks the ability of immune cells to recirculate and migrate within secondary lymphoid organs demonstrating that functional immune responses require not only immune cells themselves but also access of these cells to the site of inoculation and their unimpeded movement. The absence of humoral and T cell responses in fingolimod-treated MS patients suggests that these patients are at risk for severe SARS-CoV-2 infections despite vaccination, which is highly relevant for clinical decision-making and adapted protective measures, particularly in light of additional recently approved S1P receptor antagonists for MS treatment.
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BackgroundWhereas the majority of children under 6 years of age attend daycare centers in Germany, evidence on the role of daycare centers in the transmission of SARS-CoV-2 is scarce. AimsThis study aims to investigate the transmission risk in daycare centers among children and staff and the spread of infections to associated households. Methods30 daycare groups with at least one recent laboratory-confirmed SARS-CoV-2 case (child or staff) were enrolled in the study (10/2020-06/2021). Close contacts within the daycare group and households were examined over a 12-day period (repeated SARS-CoV-2 PCR tests, genetic sequencing of viruses, documentation of symptoms). Households, local health authorities and daycare staff were interviewed to gain comprehensive information on each outbreak. We determined primary cases for all daycare groups. ResultsThe number of secondary cases varied considerably between daycare groups. The pooled secondary attack rate (SAR) across all 30 daycare centers was 9.6%. The SAR tended to be higher in daycare centers in which the Alpha variant of the virus was detected (15.9% vs. 5.1% with evidence of wild type). The SAR in households was 53.3%. Exposed children were less likely to get infected with SARS-CoV-2 in daycare centers, compared to adults (7.7% vs. 15.5%). ConclusionContainment measures in daycare programs are critical and become increasingly important with highly transmissible new variants to reduce SARS-CoV-2 transmission, especially to avoid spread to associated households. Virus variants may modify transmission dynamics in daycare programs.
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Pre-vaccine SARS-CoV-2 seroprevalence data from Germany are scarce outside hotspots, and socioeconomic disparities remained largely unexplored. The nationwide RKI-SOEP study with 15,122 adult participants investigated seroprevalence and testing in a supplementary wave of the Socio-Economic-Panel conducted predominantly in October-November 2020. Self-collected oral-nasal swabs were PCR-positive in 0.4% and Euroimmun anti-SARS-CoV-2-S1-IgG ELISA from dry capillary blood in 1.3% (95% CI 0.9-1.7%, population-weighted, corrected for sensitivity=0.811, specificity=0.997). Seroprevalence was 1.7% (95% CI 1.2-2.3%) when additionally adjusting for antibody decay. Overall infection prevalence including self-reports was 2.1%. We estimate 45% (95% CI 21-60%) undetected cases and analyses suggest lower detection in socioeconomically deprived districts. Prior SARS-CoV-2 testing was reported by 18% from the lower educational group compared to 25% and 26% from the medium and high educational group (p<0.0001). Symptom-triggered test frequency was similar across educational groups. However, routine testing was more common in low-educated adults, whereas travel-related testing and testing after contact with an infected person was more common in highly educated groups. In conclusion, pre-vaccine SARS-CoV-2-seroprevalence in Germany was very low. Notified cases appear to capture more than half of infections but may underestimate infections in lower socioeconomic groups. These data confirm the successful containment strategy of Germany until winter 2020.
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BackgroundHigh-throughput detection of neutralizing antibodies against SARS-CoV-2 presents a valuable tool for vaccine trials or investigations of population immunity. We evaluate the performance of the first commercial surrogate virus neutralization test (sVNT, GenScript Biotech) against SARS-CoV-2 plaque reduction neutralization test (PRNT) in convalescent and vaccinated individuals. We compare it to five other ELISAs, two of which are designed to detect neutralizing antibodies. ResultsIn 491 pre-vaccination serum samples, sVNT missed 23.6% of PRNT-positive samples when using the manufacturer-recommended cutoff of 30% binding inhibition. Introducing a equivocal area between 15 and 35% maximized sensitivity and specificity against PRNT to 72.8-93.1 % and 73.5- 97.6%, respectively. The overall diagnostic performance of the other ELISAs for neutralizing antibodies was below that of sVNT. Vaccinated individuals exhibited higher antibody titers by PRNT (median 119.8, IQR 56.7-160) and binding inhibition by sVNT (median 95.7, IQR 88.1-96.8) than convalescent patients (median 49.1, IQR 20-62; median 52.9, IQR 31.2-76.2). ConclusionGenScript sVNT is suitable to screen for SARS-CoV-2-neutralizing antibodies; however, to obtain accurate results, confirmatory testing by PRNT in a equivocal area is required. This equivocal area may require adaptation for use in vaccinated individuals, due to higher antibody titers.
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BackgroundThe detection of SARS-CoV-2 with rapid diagnostic tests has become an important tool to identify infected people and break infection chains. These rapid diagnostic tests are usually based on antigen detection in a lateral flow approach. Aims & MethodsWhile for PCR diagnostics the validation of a PCR assay is well established, for antigen tests e.g. rapid diagnostic tests there is no common validation strategy. Here we present the establishment of a panel of 50 pooled clinical specimens that cover a SARS-CoV-2 concentration range from approximately 1.1 x 109 to 420 genome copies per mL of specimen. The panel was used to evaluate 31 rapid diagnostic tests in up to 6 laboratories. ResultsOur results show that there is significant variation in the detection limits and the clinical sensitivity of different rapid diagnostic tests. We conclude that the best rapid diagnostic tests can be applied to reliably identify infectious individuals who are presenting with SARS-CoV-2 loads correlated to 106 genome copies per mL of specimen. Infected individuals displaying SARS-CoV-2 genome loads corresponding to less than 106 genome copies per mL will be identified by only some rapid diagnostics tests, while many tests miss these viral loads to a large extent. ConclusionsSensitive RDTs can be applied to identify infectious individuals with high viral loads, but not to identify infected individuals.
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ObjectiveIndependent evaluation of the sensitivity of CE-marked SARS-CoV-2 antigen rapid diagnostic tests (Ag RDT) offered in Germany. MethodThe sensitivity of 122 Ag RDT was adressed using a common evaluation panel. Minimum sensitivity of 75% for panel members with CT<25 was used for differentiation of devices eligible for reimbursement in in the German healthcare system. ResultsThe sensitivity of different SARS-CoV-2 Ag RDT varied over a wide range. The sensitivity limit of 75% for panel members with CT <25 was met by 96 of the 122 tests evaluated; 26 tests exhibited lower sensitivity, few of which were completely failing. Some devices exhibited high sensitivity, e.g. 100% for CT<30. ConclusionThis comparative evaluation succeeded to distinguish less sensitive from better performing Ag RDT. Most of the Ag RDT evaluated appear to be suitable for fast identification of acute infections associated with high viral loads. Market access of SARS-CoV-2 Ag RDT should be based on minimal requirements for sensitivity and specificity.
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Summary/AbstractO_ST_ABSIntroductionC_ST_ABSContainment of the COVID-19 pandemic requires broad-scale testing. Laboratory capacities for real-time-PCR were increased, and are complemented by Ag-tests. However, sample-collection still requires qualified personnel and protective equipement, may produce transmission to others during conduct and travel, and is perceived uncomfortable. We tested sensitivity of three simplified self-sampling techniques compared to professional-collected combined oro-nasopharyngeal samples (cOP/NP). MethodsFrom 62 symptomatic COVID-19 outpatients, we obtained simultaneously three self- and one professional-collected sample after initial confirmation in a testing centre: (i) combination swab (tongue, cheek, both nasal vestibula, MS, (ii) saliva sponge combined with both nasal vestibula, SN, and (iii) gargled tap water, GW, (iv) professionally-collected cOP/NP (standard). We compared the results of SARS-CoV-2 PCR-assays detecting E-gene and ORF1ab for the different sample types and performed bivariate statistical analysis to determine the variables reducing sensitivity of the self-collecting procedures. ResultsSARS-CoV-2 RNA was detected in all 62 professionally-collected cOP/NP. MS and SN samples showed a sensitivity of 95.2% (95%CI 86.5-99.0) and GW samples of 88.7% (78.1-95.3). Compared to the median ct-values of cOP/NP samples for E-gene (20.7) and ORF1ab (20.2) these were higher for MS (22.6 and 21.8), SN (23.3 and 22.3), and for GW (30.3 and 29.8). For MS and SN samples but not for GW specimens, false negativity in bivariate analysis was associated with non-German mother-tongue, number of sampling errors, and with symptom duration. For symptom duration of [≤]8 days, test sensitivity for SN samples was 98.2% (95%CI 90.4-100.0) and for MS 96.4% (95%CI 87.7-99.6) and drops after day 8 below 90%. DiscussionThe study is limited to sensitivity of self-collection in symptomatic patients. Still, in this group, self-collected oral/nasal/saliva samples are reliable alternatives to professional-collected cOP/NP samples, if symptom duration does not exceed eight days and operational errors are minimized. Self-sampling could contribute to up-scaling of safe and efficient testing.
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Point of care detection of SARS-CoV-2 is one pillar in a containment strategy and important to break infection chains. Here we report the sensitive, specific and robust detection of SARS-CoV-2 and respective variants of concern by the ID NOW COVID-19 device.
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SARS-CoV and SARS-CoV-2 infections are characterized by remarkable differences, including contagiosity and case fatality rate. The underlying mechanisms are not well understood, illustrating major knowledge gaps of coronavirus biology. In this study, protein expression of SARS-CoV- and SARS-CoV-2-infected human lung epithelial cell line Calu-3 was analysed using data-independent acquisition mass spectrometry (DIA-MS). This resulted in the so far most comprehensive map of infection-related proteome-wide expression changes in human cells covering the quantification of 7478 proteins across 4 time points. Most notably, the activation of interferon type-I response was observed, which surprisingly is absent in other recent proteome studies, but is known to occur in SARS-CoV-2-infected patients. The data reveal that SARS-CoV-2 triggers interferon-stimulated gene (ISG) expression much stronger than SARS-CoV, which reflects the already described differences in interferon sensitivity. Potentially, this may be caused by the enhanced expression of viral M protein of SARS-CoV in comparison to SARS-CoV-2, which is a known inhibitor of type I interferon expression. This study expands the knowledge on the host response to SARS-CoV-2 infections on a global scale using an infection model, which seems to be well suited to analyse innate immunity.
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SARS-CoV-2 is the causative of the COVID-19 disease, which has spread pandemically around the globe within a few months. It is therefore necessary to collect fundamental information about the disease, its epidemiology and treatment, as well as about the virus itself. While the virus has been identified rapidly, detailed ultrastructural analysis of virus cell biology and architecture is still in its infancy. We therefore studied the virus morphology and morphometry of SARS-CoV-2 in comparison to SARS-CoV as it appears in Vero cell cultures by using conventional thin section electron microscopy and electron tomography. Both virus isolates, SARS-CoV Frankfurt 1 and SARS-CoV-2 Italy-INMI1, were virtually identical at the ultrastructural level and revealed a very similar particle size distribution with a median of about 100 nm without spikes. Maximal spike length of both viruses was 23 nm. The number of spikes per virus particle was about 30% higher in the SARS-CoV than in the SARS-CoV-2 isolate. This result complements a previous qualitative finding, which was related to a lower productivity of SARS-CoV-2 in cell culture in comparison to SARS-CoV.
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The newly identified severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19, a pandemic respiratory disease presenting with fever, cough, and often pneumonia. Moreover, thromboembolic events throughout the body including the central nervous system (CNS) have been described. Given first indication for viral RNA presence in the brain and cerebrospinal fluid and in light of neurological symptoms in a large majority of COVID-19 patients, SARS-CoV-2-penetrance of the CNS is likely. By precisely investigating and anatomically mapping oro- and pharyngeal regions and brains of 32 patients dying from COVID-19, we not only describe CNS infarction due to cerebral thromboembolism, but also demonstrate SARS-CoV-2 neurotropism. SARS-CoV-2 enters the nervous system via trespassing the neuro-mucosal interface in the olfactory mucosa by exploiting the close vicinity of olfactory mucosal and nervous tissue including delicate olfactory and sensitive nerve endings. Subsequently, SARS-CoV-2 follows defined neuroanatomical structures, penetrating defined neuroanatomical areas, including the primary respiratory and cardiovascular control center in the medulla oblongata.
