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1.
researchsquare; 2022.
Preprint in English | PREPRINT-RESEARCHSQUARE | ID: ppzbmed-10.21203.rs.3.rs-1226339.v1

ABSTRACT

Infection-neutralizing antibody responses after SARS-CoV-2 infection or COVID-19 vaccination are an essential part of antiviral immunity. This immune protection is challenged by the occurrence of SARS-CoV-2 variants of concern (VoCs) with immune escape properties, such as omicron (B.1.1.529) that is rapidly spreading worldwide. Here, we report neutralizing antibody dynamics in a longitudinal cohort of COVID-19 convalescent and naïve individuals vaccinated with mRNA BNT162b2 by quantifying anti-SARS-CoV-2-spike antibodies and determining their avidity and neutralization capacity. A superior infection-neutralizing capacity against all VoCs, including omicron, developed by either two vaccinations of convalescents, or a third vaccination or breakthrough infection of twice-vaccinated naïve individuals. These three consecutive spike antigen exposures resulted in an increasing neutralization capacity per anti-spike antibody unit and were paralleled by stepwise increases in antibody avidity. In conclusion, an infection/vaccination-induced hybrid immunity or a triple immunization induces high-quality antibodies resulting in superior neutralization capacity against VoCs, including omicron.


Subject(s)
COVID-19
2.
medrxiv; 2021.
Preprint in English | medRxiv | ID: ppzbmed-10.1101.2021.04.17.21255651

ABSTRACT

Children have been disproportionately affected during the COVID-19 pandemic. We aimed to assess a saliva-based algorithm for SARS-CoV-2 testing to be used in schools and childcare institutions under pandemic conditions. A weekly SARS-CoV-2 sentinel study in primary schools, kindergartens and childcare facilities was conducted over a 12-week-period. In a sub-study covering 7 weeks, 1895 paired oropharyngeal and saliva samples were processed for SARS-CoV-2 rRT-PCR testing in both asymptomatic children (n=1243) and staff (n=652). Forty-nine additional concurrent swab and saliva samples were collected from SARS-CoV-2 infected patients (patient cohort). The Salivette® system was used for saliva collection and assessed for feasibility and diagnostic performance. For children a mean of 1.18 ml saliva could be obtained. Based on results from both cohorts, the Salivette® testing algorithm demonstrated specificity of 100% (95% CI 99.7 - 100) and sensitivity of 94.9% (95% CI 81.4 - 99.1) with oropharyngeal swabs as reference. Agreement between sampling systems was 100% for moderate to high viral load situations (defined as Ct-values < 33 from oropharyngeal swabs). Comparative analysis of Ct-values derived from saliva vs. oropharyngeal swabs demonstrated a significant difference (mean 4.23; 95% CI 2.48–6.00). In conclusion, the Salivette® system proved to be an easy-to-use, safe and feasible saliva collection method and a more pleasant alternative to oropharyngeal swabs for SARS-CoV-2 testing in children aged 3 years and above.


Subject(s)
COVID-19
3.
medrxiv; 2021.
Preprint in English | medRxiv | ID: ppzbmed-10.1101.2021.02.19.21252080

ABSTRACT

Background Quantitative serological assays detecting response to SARS-CoV-2 infection are urgently needed to quantify immunity. This study analyzed the performance and correlation of two independent quantitative anti-S1 assays in oligo-/asymptomatic individuals from a previously characterized population-based cohort. Methods A total of 362 samples included 108 from individuals who had viral RNA detected in pharyngeal swabs, 111 negative controls and 143 samples with positive serology but not confirmed by RT-PCR. Blood plasma was tested with quantitative assays Euroimmun Anti-SARS-CoV-2 QuantiVac ELISA (IgG) (EI-S1-IgG-quant) and Roche Elecsys ® Anti-SARS-CoV-2 CoV-2 S (Ro-RBD-Ig-quant), which were compared with each other and with confirmatory tests, including wild-type virus micro-neutralization (NT) and GenScript ® cPass™. Results were analyzed using square roots R of coefficients of determination for association among continuous variables and non-parametric tests for paired comparisons. Results Quantitative anti-S1 serology correlated well with each other (96%/97% for true-positives and true-negatives, respectively). Antibody titers decreased over time (from <30 days to >240 days after initial positive RT-PCR). Agreement with GenScript-cPass was 96%/99% for true-positives and true-negatives, respectively, for Ro-RBD-Ig-quant and 93%/97% for EI-S1-IgG-quant. Ro-RBD-Ig-quant allowed a distinct separation between positive and negative values, and less non-specific reactivity compared with EI-S1-IgG-quant. Raw values (with 95% CI) ≥28.7 U/mL (22.6–36.4) for Ro-RBD-Ig-quant and ≥49.8 U/mL (43.4–57.1) for EI-S1-IgG-quant predicted virus neutralization >1:5 in 95% of cases. Conclusions Both quantitative anti-S1 assays, Ro-RBD-Ig-quant and EI-S1-IgG-quant, may replace direct neutralization assays in quantitative measurement of immune protection against SARS-CoV-2 in certain circumstances in the future. Key points Two quantitative anti-S1 assays showed similar performance and a high level of agreement with direct virus neutralization and surrogate neutralization tests, arguing for their utility in quantifying immune protection against SARS-CoV-2.


Subject(s)
COVID-19
4.
medrxiv; 2021.
Preprint in English | medRxiv | ID: ppzbmed-10.1101.2021.01.22.21249971

ABSTRACT

A 12-week sentinel programme monitored SARS-CoV-2 in primary schools, kindergartens and nurseries. Out of 3169 oropharyngeal swabs, only two tested positive on rRT-PCR while general incidence rates were surging. Thus, children attending respective institutions are not significantly contributing to the pandemic spread when appropriate infection control measures are in place.

5.
medrxiv; 2021.
Preprint in English | medRxiv | ID: ppzbmed-10.1101.2021.01.13.21249735

ABSTRACT

BackgroundSerosurveys are essential to understand SARS-CoV-2 exposure and enable population-level surveillance, but currently available tests need further in-depth evaluation. We aimed to identify testing-strategies by comparing seven seroassays in a population-based cohort. MethodsWe analysed 6,658 samples consisting of true-positives (n=193), true-negatives (n=1,091), and specimens of unknown status (n=5,374). For primary testing, we used Euroimmun-Anti-SARS-CoV-2-ELISA-IgA/IgG and Roche-Elecsys-Anti-SARS-CoV-2; and virus-neutralisation, GeneScript(R)cPass, VIRAMED-SARS-CoV-2-ViraChip(R), and Mikrogen-recomLine-SARS-CoV-2-IgG, including common-cold CoVs, for confirmatory testing. Statistical modelling generated optimised assay cut-off-thresholds. FindingsSensitivity of Euroimmun-anti-S1-IgA was 64.8%, specificity 93.3%; for Euroimmun-anti-S1-IgG, sensitivity was 77.2/79.8% (manufacturers/optimised cut-offs), specificity 98.0/97.8%; Roche-anti-N sensitivity was 85.5/88.6%, specificity 99.8/99.7%. In true-positives, mean and median titres remained stable for at least 90-120 days after RT-PCR-positivity. Of true-positives with positive RT-PCR (<30 days), 6.7% did not mount detectable seroresponses. Virus-neutralisation was 73.8% sensitive, 100.0% specific (1:10 dilution). Neutralisation surrogate tests (GeneScript(R)cPass, Mikrogen-recomLine-RBD) were >94.9% sensitive, >98.1% specific. Seasonality had limited effects; cross-reactivity with common-cold CoVs 229E and NL63 in SARS-CoV-2 true-positives was significant. ConclusionOptimised cut-offs improved test performances of several tests. Non-reactive serology in true-positives was uncommon. For epidemiological purposes, confirmatory testing with virus-neutralisation may be replaced with GeneScript(R)cPass or recomLine-RBD. Head-to-head comparisons given here aim to contribute to the refinement of testing-strategies for individual and public health use.


Subject(s)
COVID-19 , Severe Acute Respiratory Syndrome
6.
ssrn; 2020.
Preprint in English | PREPRINT-SSRN | ID: ppzbmed-10.2139.ssrn.3551335

ABSTRACT

Background: In December 2019, a newly identified coronavirus (SARS-CoV-2) emerged in Wuhan, China, causing respiratory disease (COVID-19) presenting with fever, cough and frequently pneumonia. WHO has set the strategic objective to interrupt virus spread of SARS-CoV-2 worldwide. An outbreak in Bavaria, Germany, starting end of January 2020, gave the opportunity to study transmission events, incubation period, and attack rates.Methods: A case was defined as a person with SARS-CoV-2-infection confirmed by PCR. Case interviews were conducted to i) describe timing of onset and nature of symptoms, ii) identify and classify contacts. High-risk contacts were actively followed and monitored for symptoms, low-risk contacts were tested upon self-reporting of symptoms. Whole genome sequencing was used to confirm epidemiological links and clarify transmission events where contact histories were ambiguous; integration with epidemiological data enabled precise reconstruction of exposure events and incubation periods.Results: Case #0 was a Chinese person who visited Germany for professional reasons. Sixteen subsequent cases emerged in four transmission generations. Signature mutations occurred upon foundation of generation 2, as well as in one patient pertaining to generation 4. Median incubation period and serial interval were 4.0 days, respectively. Transmissions occurred frequently pre-symptomatic, at day of symptom onset and during prodromal phase (symptoms other than fever and cough for ≥1 day at beginning of illness phase). Attack rates were 75% among members of a household cluster in common isolation, 10% among household contacts only together until isolation of case, and 5% among non-household high-risk contacts.Conclusions: While our cases present with predominately mild, non-specific symptoms, infectiousness before or on the day of symptom onset or during prodromal phase is substantial. Additionally, the incubation period is often very short, false-negative tests may occur. Although the outbreak was apparently controlled, successful long-term and global containment of COVID-19 may be difficult to achieve.Funding Statement: Contributions by C. D. and V. M. C. were funded by the German Ministry of Health (Konsiliarlabor für Coronaviren), as well as the German Center for Infection Research. S.B., T.W., K.P., N.M, and T.S.B. are fellows of the ECDC Fellowship Programme, supported financially by the European Centre for Disease Prevention and Control (ECDC).Declaration of Interests: The authors declared no competing interest. Ethics Approval Statement: The outbreak investigation was conducted as part of the authoritative, official tasks of the county health departments as well as the state health department of the Bavarian Health and Food Safety Authority, supported by the Robert Koch Institute. As conducted in response to a public health emergency, this study was exempt from institutional review board approval.


Subject(s)
Pneumonia , COVID-19 , Fever , Protein S Deficiency
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