Cycle threshold of SARS-CoV-2 RT-PCR as a driver of retesting

Abstract SARS-CoV-2 RT-PCR is a critical and, at times, limited resource. Frequent Retesting of patients may strain testing infrastructure unduly. Recommendations that include cycle threshold (Ct) cutoffs may incentivize early retesting when the Ct value is reported. We aimed to investigate patterns of retesting in association with initial Ct-values. We performed a retrospective analysis of RT-PCR results (including Ct-values) for patients from whom ≥ 2 samples were collected within 14 days, the first of which had to be positive. We calculated absolute and baseline-corrected kinetics of Ct-values over time, as well as the median initial Ct-values in dependence of the timing of the first retesting and the time until RT-PCR negativity for SARS-CoV-2. Retesting after an initial positive SARS-CoV-2 RT-PCR was most commonly performed on day 7, with patients being retested as early as day 1. The majority of patients retested within 14 days remained SARS-CoV-2 positive in the RT-PCR. Baseline-corrected Ct-values showed a quasi-linear increase over 14 days since the initial positive result. Both the timing until the first retesting and until RT-PCR negativity were inversely correlated with the initial Ct-value. The timing of retesting after a positive SARS-CoV-2 RT-PCR appears to be significantly influenced by the initial Ct-value. Although it can be assumed that Ct-values will increase steadily over time, strategies that rely on rigid Ct-cutoffs should be discussed critically, not only because of methodological caveats but also because of the strain on testing infrastructure caused by the incentive for early retesting that Ct-values apparently represent

The role of neuronal antibodies in cryptogenic new‐onset refractory status epilepticus

Most cases with new‐onset refractory status epilepticus (NORSE) remain cryptogenic despite extensive diagnostic work‐up. The aim of this study was to analyse the etiology and clinical features of NORSE and investigate known or potentially novel autoantibodies in cryptogenic NORSE (cNORSE). We retrospectively assessed the medical records of adults with status epilepticus at a Swiss tertiary referral center between 2010 and 2021. Demographic, diagnostic, therapeutic and outcome parameters were characterized. We performed post‐hoc screening for known or potentially novel autoantibodies including immunohistochemistry (IHC) on rat brain with CSF and serum samples of cNORSE. 20 patients with NORSE were identified. Etiologies included infections (n=4), Creutzfeld‐Jakob disease (n=1), CASPR2 autoimmune encephalitis (n=1), and carotid artery stenosis with recurrent perfusion deficit (n=1). Thirteen cases (65%) were cryptogenic despite detailed evaluation. A posteriori IHC for neuronal autoantibodies yielded negative results in all available serum (n=11) and CSF (n=9) samples of cNORSE. Our results suggest that neuronal antibodies are unlikely to play a major role in the pathogenesis of cNORSE. Future studies should rather focus on other – especially T‐cell‐ and cytokine‐mediated – mechanisms of autoinflammation in this devastating disease, which is far too poorly understood so far

Analysis of SARS-CoV-2 reverse transcription-quantitative polymerase chain reaction cycle threshold values vis-à-vis anti-SARS-CoV-2 antibodies from a high incidence region

OBJECTIVES: To examine the relationship between antibody status and cycle threshold (Ct) values, the prognostic value of the latter for COVID-19 patients, and the inter-assay comparability of SARS-CoV-2 Ct values. METHODS: In 347 COVID-19 inpatients, SARS-CoV-2 Ct values (via reverse transcription-quantitative polymerase chain reaction) on admission were compared between 2 assays and correlated with the antibody response (in the course of the disease), the clinical course and the time since onset of symptoms. RESULTS: Ct values for 2 of 3 target genes showed significant differences between the 2 assays used (P=0.012 and P<0.0001). Ct values were significantly higher for antibody positive patients (P<0.0001) and positively correlated with the amount of time since onset of symptoms (R: 0.332-0.363; P<0.001). Patients with fatal outcomes showed higher viral loads than survivors (P<0.0001). CONCLUSIONS: Ct values depend strongly on assay used and target gene examined and should not be used as quantitative values to guide therapeutic or diagnostic decisions. The inverse association between antibody status and viral load suggests that antibodies contribute to the elimination of the virus, independent of the outcome, which is influenced by the viral load on admission and might depend more strongly on other parts of the immune response

Differences in Immunogenicity of Three Different Homo- and Heterologous Vaccination Regimens against SARS-CoV-2

Background: Due to findings on adverse reactions and clinical efficacy of different vaccinations against SARS-CoV-2, the administration of vaccination regimens containing both adenoviral vector vaccines and mRNA-based vaccines has become common. Data are still needed on the direct comparison of immunogenicity for these different regimens. Methods: We compared markers for immunogenicity (anti-S1 IgG/IgA, neutralizing antibodies, and T-cell response) with three different vaccination regimens (homologous ChAdOx1 nCoV-19 (n = 103), or mixture of ChAdOx1 nCoV-19 with mRNA-1273 (n = 116) or BNT162b2 (n = 105)) at two time points: the day of the second vaccination as a baseline and 14 days later. Results: All examined vaccination regimens elicited measurable immune responses that were significantly enhanced after the second dose. Homologous ChAdOx1 nCoV-19 was markedly inferior in immunogenicity to all other examined regimens after administration of the second dose. Between the heterologous regimens, mRNA-1273 as second dose induced greater antibody responses than BNT162b2, with no difference found for neutralizing antibodies and T-cell response. Discussion: While these findings allow no prediction about clinical protection, from an immunological point of view, vaccination against SARS-CoV-2 with an mRNA-based vaccine at one or both time points appears preferable to homologous vaccination with ChAdOx1 nCoV-19. Whether or not the demonstrated differences between the heterologous regimens are of clinical significance will be subject to further research

sj-jpg-6-wso-10.1177_17474930231152124 – Supplemental material for Characterizing mixed location hemorrhages/microbleeds with CSF markers

Supplemental material, sj-jpg-6-wso-10.1177_17474930231152124 for Characterizing mixed location hemorrhages/microbleeds with CSF markers by Ulf Jensen-Kondering, Nils G Margraf, Caroline Weiler, Walter Maetzler, Justina Dargvainiene, Kim Falk, Sarah Philippen, Thorsten Bartsch, Charlotte Flüh, Christoph Röcken, Bettina Möller, Georg Royl, Alexander Neumann, Norbert Brüggemann, Benjamin Roeben, Claudia Schulte, Benjamin Bender, Daniela Berg and Gregor Kuhlenbäumer in International Journal of Stroke</p

sj-jpg-3-wso-10.1177_17474930231152124 – Supplemental material for Characterizing mixed location hemorrhages/microbleeds with CSF markers

Supplemental material, sj-jpg-3-wso-10.1177_17474930231152124 for Characterizing mixed location hemorrhages/microbleeds with CSF markers by Ulf Jensen-Kondering, Nils G Margraf, Caroline Weiler, Walter Maetzler, Justina Dargvainiene, Kim Falk, Sarah Philippen, Thorsten Bartsch, Charlotte Flüh, Christoph Röcken, Bettina Möller, Georg Royl, Alexander Neumann, Norbert Brüggemann, Benjamin Roeben, Claudia Schulte, Benjamin Bender, Daniela Berg and Gregor Kuhlenbäumer in International Journal of Stroke</p

sj-docx-1-wso-10.1177_17474930231152124 – Supplemental material for Characterizing mixed location hemorrhages/microbleeds with CSF markers

Supplemental material, sj-docx-1-wso-10.1177_17474930231152124 for Characterizing mixed location hemorrhages/microbleeds with CSF markers by Ulf Jensen-Kondering, Nils G Margraf, Caroline Weiler, Walter Maetzler, Justina Dargvainiene, Kim Falk, Sarah Philippen, Thorsten Bartsch, Charlotte Flüh, Christoph Röcken, Bettina Möller, Georg Royl, Alexander Neumann, Norbert Brüggemann, Benjamin Roeben, Claudia Schulte, Benjamin Bender, Daniela Berg and Gregor Kuhlenbäumer in International Journal of Stroke</p

sj-jpg-4-wso-10.1177_17474930231152124 – Supplemental material for Characterizing mixed location hemorrhages/microbleeds with CSF markers

Supplemental material, sj-jpg-4-wso-10.1177_17474930231152124 for Characterizing mixed location hemorrhages/microbleeds with CSF markers by Ulf Jensen-Kondering, Nils G Margraf, Caroline Weiler, Walter Maetzler, Justina Dargvainiene, Kim Falk, Sarah Philippen, Thorsten Bartsch, Charlotte Flüh, Christoph Röcken, Bettina Möller, Georg Royl, Alexander Neumann, Norbert Brüggemann, Benjamin Roeben, Claudia Schulte, Benjamin Bender, Daniela Berg and Gregor Kuhlenbäumer in International Journal of Stroke</p

sj-jpg-5-wso-10.1177_17474930231152124 – Supplemental material for Characterizing mixed location hemorrhages/microbleeds with CSF markers

Supplemental material, sj-jpg-5-wso-10.1177_17474930231152124 for Characterizing mixed location hemorrhages/microbleeds with CSF markers by Ulf Jensen-Kondering, Nils G Margraf, Caroline Weiler, Walter Maetzler, Justina Dargvainiene, Kim Falk, Sarah Philippen, Thorsten Bartsch, Charlotte Flüh, Christoph Röcken, Bettina Möller, Georg Royl, Alexander Neumann, Norbert Brüggemann, Benjamin Roeben, Claudia Schulte, Benjamin Bender, Daniela Berg and Gregor Kuhlenbäumer in International Journal of Stroke</p