A comprehensive analysis of recovered COVID-19 patients and dynamic trend in antibodies over 3 months using ELISA and CLIA methods

  1. Puya Dehgani-Mobaraki
  2. Asiya Kamber Zaidi
  3. Alessandro Floridi
  4. Alessandro Lepri
  5. Emanuela Floridi
  6. Alessia Gherardi
  7. Enrico Bernini-Carri
  8. Eleonora D’urzo
  9. Massoud Dehgani-Mobaraki

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Abstract

Background

Since the Coronavirus disease-2019 outbreak, most studies have focused on etiopathogenic aspects and treatment strategies. Acquired immunity still remains a dilemma. The aim of our study included a comprehensive analysis of patient characteristics, evaluation of antibody response, and its trend over a period of three months in recovered patients.

Methods

Monocentric investigator-initiated pilot longitudinal observational study conducted by the Association Naso Sano, on a cohort of 30 COVID recovered patients based in the Umbria region, followed up from April to June 2020 for baseline blood counts, IgM and IgG trends using two different serological assays-ELISA and CLIA. The demographics, blood group, co-morbidities and treatment modalities were recorded from each patient along with an analysis of clinical profile, dates concerning symptom onset, first positive and two consecutive negative swabs using an online questionnaire followed by serological testing. Descriptive and Bivariate (Pearson correlation coefficient) statistics were conducted to detect statistically significant correlations.

Findings

The study involved 30 patients with a M:F ratio of 0.57 and a distribution of mild (67%), moderate (30%) and critical (3%). Majority of the patients were healthcare workers (40%) and the mean viral shedding duration was 20.13 ± 6.17 days. The IgG levels offered long-standing protection as long as 3 months in some cases. A statistically significant, directly proportional correlation (Pearson) exists between ELISA and CLIA values for IgM. Some patients also expressed titers lower than the detection threshold and therefore a positive RT-PCR test does not necessarily guarantee a high IgG response in the recovery period.

Interpretation

The data presented in our study provides a relative long-term analysis and possible explanation regarding the protection developed by patients recovered from COVID-19.

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    SciScore for 10.1101/2020.08.31.20184838: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementIRB: This study was approved by the Research ethics committee of Association Naso Sano [Document number: ANS-2020/001].
    Consent: [1] Post recovery they were invited for serial serological tests by one of the authors, P.D.M, who had tested positive earlier this year and is also currently a part of the study sample.[2] Out of the 33 patients enrolled, three were excluded from the study: a 3 months old infant in view of negative consent from the parents for blood sampling and 2 patients who did not report for consecutive tests, making a final sample size of 30 patients.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    Analytical systems used in our study: Statistical Analysis: Statistical analysis was carried out using SPSS [version 25, IBM] and statistical functions were used to plot co-relations between variables.
    SPSS
    suggested: (SPSS, RRID:SCR_002865)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    The limitations of our study included its small sample size (30) and analysis of only the antibody titers which might not be sufficient to assess the overall immunity of the patient, as some studies have proven that both, the lymphoid and myeloid immunity have a role to play in offering protection against future infection. [15] While the humoral immunity comprises the action of antibodies developed against the infection; the Cell-mediated immunity involves the action of T cells. Yet another limitation could be the fact that the relationship of the measured antibodies with that of neutralizing activity against SARS-CoV-2 was not evaluated. The neutralizing antibodies are detected by the Plaque reduction neutralization test (PRNT), which requires a live virus and a biosafety level of 3. Few studies, however, have demonstrated the antibodies that target different domains of S protein, including S1, RBD, and S2 might contribute to “virus neutralization”. [16, 17] Inhomogeneity of the sample concerning blood groups and clinical severity could be attributed to the study being cross-sectional and observational. Moreover, most of these assays in the market are based on studies conducted on severe hospitalized patients [13] creating a “spectrum bias” and so these might not be generalized for patients with mild symptoms.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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  2. Version published to 10.1101/2020.08.31.20184838v1 on medRxiv