ABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first emerged at the end of 2019, causing the coronavirus disease (COVID-19). The main sources of infections are infected and asymptomatic persons. One major problem of the pandemic are the diverse symptoms and the varying manifestations of the illness. In this study, the IgG level recognizing the RBD of SARS-CoV-2 was determined within 336 volunteers from the environment of the University of Applied Sciences Wiener Neustadt. The aims of this study were to identify the estimated number of undiscovered COVID-19 infections and the corresponding antibody levels. In total, 11.3% of the nonvaccinated probands had a positive IgG antibody titer against SARS-CoV-2, whereas 4.0% did not test positive for SARS-CoV-2 or had never been tested at the time of sampling. Probands in this study reported tiredness (57,5%), ageusia/anosmia (55%) and headache (47,5%) as most frequent symptoms.Copyright © 2021
ABSTRACT
In November 2020, the Armed Forces of the Russian Federation began mass immunisation of the personnel with Gam-COVID-Vac (Sputnik V), the first Russia vaccine against the new coronavirus infection (COVID-19). Thus, it became necessary to assess post-vaccination antibody levels and the duration and intensity of humoral immunity to COVID-19. The aim of the study was to investigate the immunogenicity and efficacy of Gam-COVID-Vac in military medical staff after vaccination. Material(s) and Method(s): the authors determined the presence of specific antibodies in the serum of individuals immunised with Gam-COVID-Vac (477 volunteers) and COVID-19 convalescents (73 patients), using virus neutralisation (VN), enzyme-linked immunosorbent assay (ELISA) with reagent kits by several manufacturers, and immunoblotting. The results of the study were evaluated using analysis of variance. Result(s): VN detected virus neutralising antibodies in 90.7% of vaccinated subjects;ELISA, in 95.4%. Both VN and ELISA showed lower antibody levels in the vaccinated over 50 years of age. ELISA demonstrated a significantly higher concentration of anti-SARS-CoV-2 spike IgG in the Gam-COVID-Vac group than in the COVID-19 convalescent group. The correlation between antibody detection results by VN and ELISA was the strongest when the authors used their experimental reagent kit for quantitative detection of virus neutralising antibodies by competitive ELISA with the recombinant human ACE2 receptor. Having analysed the time course of neutralising antibody titres, the authors noted a significant, more than two-fold decrease in geometric means of the titres three months after administration of the second vaccine component. Conclusion(s): the subjects vaccinated with Gam-COVID-Vac gain effective humoral immunity to COVID-19. The decrease in titres indicates the need for revaccination in 6 months.Copyright © 2023 Safety and Risk of Pharmacotherapy. All rights reserved.
ABSTRACT
Background and Objectives: Serological studies are based on the detection of antibodies. However, the produced antibodies decrease over time;therefore, such methods cannot provide a valid estimate of prevalence and incidence. The present study aimed to determine the serum prevalence and cumulative incidence in the Ravansar cohort population (Youth and RaNCD Cohort) in October 2020. Method(s): A random sample of 716 people aged > 18 years old were selected from the participants in the Ravansar cohort study in October 2020. Euroimmun anti-SARS COV-2 IgG ELISA kits (Lubeck, Germany) were used to measure antibody levels. Seroprevalence was estimated with considering of cut-off = 1, and cumulative incidence (modified and modified based on test specificity) was determined using modeling. Result(s): In the present study, the serum prevalence of COVID-19 viral infection in the Ravansar cohort population from 22 October 2020 to 18 November 2020 was estimated to be %35.16 (95%CI: %31.64, %38.79). Modified Cumulative incidence and modified based on test characteristics from 20 February to 18 November 2020 were estimated to be %68.85 and %67.71, respectively. Conclusion(s): Although very high cumulative incidence may be a sign of approaching herd immunity, adherence to health protocols is still recommended due to the potential role of asymptomatic cases in transmitting the disease to other members of the community;and the presence of new variants of the virus and reduced antibody levels should be considered.Copyright © 2022 The Authors.
ABSTRACT
The development of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological tests is massive. The external validation of their performance is needed before use in clinical routine practice. Our study aims at assessing the analytical and clinical performance of two enzyme-linked immunosorbent assay tests detecting antibodies directed against the virus nucleocapsid protein: The NovaLisa SARS-CoV-2 immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin M (IgM) test (NovaTec) allowing a separate detection of each antibody and the Platelia SARS-CoV-2 Total Ab test (Bio-Rad) detecting total antibodies (IgM, IgA, and IgG). Two-hundred and eight coronavirus disease 2019 samples from 48 quantitative reverse transcription-polymerase chain reaction (RT-qPCR) confirmed patients were used to perform the sensitivity analysis. Non-SARS-CoV-2 sera (n = 79) with a potential cross-reaction to SARS-CoV-2 immunoassays were included in the specificity analysis. In addition, using receiver operator characteristic curves, adapted cut-off for improvement of the performances were proposed. The kinetics of these antibodies was also assessed over 8 weeks. Two weeks after the RT-qPCR positive detection, the NovaLisa test shows a sensitivity and specificity of 94.9% (95% confidence interval [CI]: 83.1%-98.6%) and 96.2% (95% CI: 89.4%-98.7%) for IgG, of 89.7% (95% CI: 76.4%-95.9%) and 98.7% (95% CI: 93.2%-98.8%) for IgA, and of 48.7% (95% CI: 33.9%-63.8%) and 98.7% (95% CI: 93.2%-99.8%) for IgM. With the Platelia system, the specificity and sensitivity were 97.4% (95% CI: 92.1%-99.7%) and 94.9% (95% CI: 87.7%-98.0%) for total antibodies using the adapted cut-offs. The NovaLisa and the Platelia tests have satisfactory analytical performances. The clinical performances are excellent for IgG, IgA, and total antibodies especially if the cut-off is optimized.