Introduction Longevity of anti-SARS-CoV-2 antibody level and duration of immunity are current topics of major scientific interest. Antibody kinetics during the acute phase are well-studied, whereas long-term kinetics are yet to be determined and available studies are controversial. Here, results of longitudinal analysis of serological responses to SARS-CoV-2 infection after convalescent and its association with post-COVID syndrome (PCS) are reported. Material and Methods 237 serum samples were prospectively collected from 61 SARS-CoV-2 qRT-PCR-confirmed participants. Anti-SARS-CoV-2 anti-N and anti-RBD/S1 Ig level were serially determined until 8 months after study inclusion. COVID-19 associated symptoms were assessed by a standardized questionnaire at study entry and after 6 months. Results Antibodies were detectable for 56/61 participants. Within the follow-up period, no substantial decline in the anti-SARS-CoV-2 pan-Ig levels were observed. In general, antibody levels were positively correlated with disease severity, BMI, fever, and nonsmoker status. 46.8% of the participants suffered from PCS, with olfactory and gustatory dysfunctions reported most frequently. Conclusion Study result point to stable anti-SARS-CoV-2 antibody titers and thus may indicate a long-lasting immunity. These results are in line with recently published data, and add further insights concerning asymptomatic to mild affected patients, the association with clinical features and the frequency of PCS.

No abstract

Highlights FDA-EUA approved anti-SARS-CoV-2 tests compare favorably with others. longitudinal patterns of antibody development are subject to high individual variability. comparing the assays of leading manufacturers, there are considerable differences in terms of achieved and stated sensitivity/specificity. Immune response relies on disease severity, thus need to be considered for validation.

COVID-19 in patients with hematological diseases is associated with a high mortality. Moreover, preventive vaccination demonstrated reduced efficacy and the knowledge on influencing factors is limited. In this single-center study, antibody levels of the SARS-CoV-2 spike protein were measured ≥ 2 weeks after 2nd COVID-19 vaccination with a concentration ≥ 0.8 U/mL considered positive. Between July and October 2021, in a total of 373 patients (median age 64 years, 44% women) with myeloid neoplasms (n = 214, 57%), lymphoid neoplasms (n = 124, n = 33%), and other diseases (n = 35, 10%), vaccination was performed with BNT162b2 (BioNTech), mRNA-1273 (Moderna), ChADOx1 (AstraZeneca), or a combination. A total of 229 patients (61%) were on active therapy within 3 months prior vaccination and 144 patients (39%) were previously treated or treatment naïve. Vaccination-related antibody response was negative in 56/373 patients (15%): in 39/124 patients with lymphoid neoplasms, 13/214 with myeloid neoplasms, and 4/35 with other diseases. Active treatment per se was not correlated with negative response. However, rituximab and BTK inhibitor treatment were correlated significantly with a negative vaccination response, whereas younger age and chronic myeloid leukemia (CML) disease were associated with positive response. In addition, 5 of 6 patients with myeloproliferative neoplasm (MPN) and negative vaccination response were on active treatment with ruxolitinib. In conclusion, a remarkable percentage of patients with hematological diseases had no response after 2nd COVID-19 vaccination. Multivariable analysis revealed important factors associated with response to vaccination. The results may serve as a guide for better protection and surveillance in this vulnerable patient cohort.

Background The detection of antibodies against the novel coronavirus SARS-CoV-2 is mandatory for the diagnosis, retrospective assessment of disease progression, and correct evaluation of the current infection situation in the population. Many of these assays have been launched by various manufacturers. Unfortunately, the new FDA emergency use regulations have resulted in a situation where laboratories have to perform their own validation studies. Numerous of these labs do not have the biobank needed to carry the studies out. Methods In this paper, we introduce a method that allows institutions to quickly perform a verifiation study in a low-prevalence infection situation. As proof of concept, we used the Roche Elecsys Anti-SARS-CoV-2 ECLIA assay and an SAP-based hospital information system. The Shenzhen YHLO Biotech IgM and IgG assay targetting other surface patterns, was used as confirmatory test. Results The Roche assay demonstrated a limit of detection of 0.069 COI (cutoff index) and successfully passed the performance validation according to CLSI EP15-A3. The study population of 627 in-patients exhibited an age median of 64 years and approximately 13% of the group were under intensive care at the respective time point. All included patients were tested negative for SARS-CoV-2 infection by qRT-PCR (cobas 6800®, Roche, Mannheim, Germany). Only one false positive result was obtained, resulting in a specificity for the Roche Elecsys Anti-SARS-CoV-2 test of 99.84% and a negative predictive value of 99.98%. Conclusions The anonymized use of residual material enables quick evaluation of anti-SARS-CoV-2 immunoassays, as shown in this work with the Roche Elecsys assay. Comparison of the control population with economic data makes it possible to validate the sampling set and therefore to determine diagnostic specificity. Using the chosen approach, it was shown that the Roche test achieved very good results in terms of diagnostic specificity, reproducibility and limit of detection.

No abstract

External quality assessment (EQA) is a key instrument for achieving harmonization, and thus a high quality, of diagnostic procedures. As reliable test results are crucial for accurate assessment of SARS-CoV-2 infection prevalence, vaccine response and immunity, and thus for successful management of the ongoing CoViD-19 pandemic, the Reference Institute for Bioanalytics (RfB) was the first EQA provider to offer an open scheme for anti-SARS-CoV-2 antibody detection. The main objectives of this EQA were (i) gaining insights into the current diagnostic landscape and the performance of serological tests in Europe, and (ii) providing recommendations for diagnostic improvements. Within the EQA, a blinded panel of pre-characterized human serum samples with variable anti-SARS-CoV-2 antibody titers was provided for detection of anti-SARS-CoV-2 IgG, IgA and IgM antibodies. Across the three distribution rounds in 2020, 284 laboratories from 22 countries reported a total of 3,744 results for anti-SARS-CoV-2 antibody detection using more than 24 different assays for IgG. Overall, 97/3004 results were false for anti-SARS-CoV-2 IgG, 88/248 for IgA, and 34/124 for IgM. Regarding diagnostic sensitivity and specificity, substantial differences were found between the different assays used, as well as between certified and non-certified tests. For cut-off samples, a drop in the diagnostic sensitivity to 46.3% and high inter-laboratory variability were observed. In general, this EQA highlights the current variability of anti-SARS-CoV-2 antibody detection, technical limitations with respect to cut-off samples, and the lack of harmonization of testing procedures. Recommendations are provided to help laboratories and manufacturers further improve the quality of anti-SARS-CoV-2 serological diagnostics.

Background: Longitudinal humoral SARS-CoV-2 (severe acute respiratory syndrome coronavirus type 2) immunity for up to 15 months due to vaccination, the efficacy of vaccination strategies (homologous, vector–vector versus heterologous, vector–mRNA), the influence of vaccination side effects, and the infection rate in German healthcare workers need to be investigated. Methods: In this study, 103 individuals vaccinated against SARS-CoV-2 were enrolled to examine their anti-SARS-CoV-2 anti-N- and anti-RBD/S1-Ig levels. A total of 415 blood samples in lithium heparin tubes were prospectively obtained, and a structured survey regarding medical history, type of vaccine, and vaccination reactions was conducted. Results: All participants demonstrated a humoral immune response, among whom no values decreased below the positivity cutoff. Five to six months after the third vaccination, three participants showed anti-RBD/S1 antibodies of less than 1000 U/mL. We observed higher levels for heterologous mRNA-/vector-based combinations compared to pure vector-based vaccination after the second vaccination, which is harmonized after a third vaccination with the mRNA-vaccine only in both cohorts. The incidence of vaccine breakthrough in a highly exposed cohort was 60.3%. Conclusion: Sustained long-term humoral immunity was observed, indicating the superiority of a heterologous mRNA-/vector-based combination compared to pure vector-based vaccination. There was longevity of anti-RBD/S1 antibodies of at least 4 and up to 7 months without external stimulus. Regarding vaccination reactogenity, the occurrence of local symptoms as pain at the injection site was increased after the first mRNA application compared to the vector–vector cohort with a general decrease in adverse events at later vaccination time points. Overall, a correlation between the humoral vaccination response and vaccination side effects was not observed. Despite the high prevalence of vaccine breakthroughs, these only occurred in the later course of the study when more infectious variants, which are, however, associated with milder courses, were present. These results provide insights into vaccine-related serologic responses, and the study should be expanded using additional vaccine doses and novel variants in the future.