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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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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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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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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-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.
