Monitoring of SARS-CoV-2 Specific Antibodies after Vaccination

  1. Raquel Guiomar
  2. Ana João Santos
  3. Aryse Martins Melo
  4. Inês Costa
  5. Rita Matos
  6. Ana Paula Rodrigues
  7. Irina Kislaya
  8. Anabela Santos Silva
  9. Carla Roque
  10. Carla Nunes
  11. Joaquim Aguiar
  12. Fátima Graça
  13. Antônio Silva Graça
  14. Ausenda Machado

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Abstract

Vaccination is considered the most important measure to control the COVID-19 pandemic. Extensive follow-up studies with distinct vaccines and populations are able to promote robust and reliable data to better understand the effectiveness of this pharmacologic strategy. In this sense, we present data regarding binding and neutralizing (achieved by surrogate ELISA assay) antibodies throughout time, from vaccinated and previously infected (PI) health care workers (HCW) in Portugal. We analyzed serum samples of 132 HCW, who were vaccinated and with previous SARS-CoV-2 infection. Samples were collected before vaccination (baseline, M1), at second dose vaccine uptake (M2), and 25–70 days (M3) and 150–210 days (M4) after the second dose for vaccinated individuals. The IgG (anti-RBD/S) antibody geometric mean titers found on vaccinated HCW at M2 (GM = 116.1 BAU/mL; CI: 92.3–146.1) were significantly higher than those found on PI HCW at recruitment (M1) (GM = 35.9 BAU/mL; CI:15.4–83.4), and the neutralizing antibodies (nAb) were similar between these groups, of 93.2 UI/mL (95% CI 73.2–118.5) vs. 84.1 UI/mL (95% CI 40.4–155.9), respectively. We detected around 10-fold higher IgG (anti-RBD/S) antibodies titers in M3 when compared with M2, with a slight but significant decrease in titers from 36 days after the second dose vaccine uptake. The increase of nAb titers was correlated with IgG (anti-RBD/S) antibodies titers; however, in contrast to IgG (anti-RBD/S) antibodies titers, we did not detect a decrease in the nAb titer 36 days after a second vaccine dose uptake. At M4, a decrease of 8-fold in binding IgG (anti-RBD/S) and nAb was observed. No significant differences in antibody titers were observed by sex, age or chronic diseases. Our results suggest that IgG (anti-RBD/S) antibodies titers and nAb titers could be correlated, but an ongoing follow up of the cohort is required to better understand this correlation, and the duration of the immune response.

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  1. Version published to 10.3390/vaccines10020154
  2. ScreenIT

    SciScore for 10.1101/2021.12.10.21267607: (What is this?)

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

    Table 1: Rigor

    EthicsConsent: Inclusion criteria: All staff of INSA that consent to participate of our cohort study of vaccine effectiveness against COVID-19 was included in this research project. 2.3.
    IRB: The study protocol was approved by the National Institute of Health Doctor Ricardo Jorge Health Ethics Committee.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Additionally, as “previous infection” an individual who reported a positive RT-PCR test to SARS-CoV-2 or had a positive RT-PCR test to SARS-CoV-2 and/or had anti-SARS-CoV-2 antibodies in a serum sample taken in the recruitment at Moment 1(M1), before vaccine uptake. 2.5.
    SARS-CoV-2
    suggested: None
    After a centrifugation at 2500rpm for 15min serum was obtained and conserved refrigerated (2 – 8ºC) for a maximum of 7 days before laboratorial analysis to detection of IgG antibodies and then, were stored frozen (−20ºC) until the neutralizing antibodies test was performed. 2.6. Determination of IgG antibodies: The determination of SARS-CoV-2 specific antibodies was done by a chemiluminescence enzyme immunoassay used for quantitative detection of Antireceptor-binding domain (RBD) from spike protein (S) antibodies (IgG anti-RBD/S) against SARS-CoV-2.
    Antireceptor-binding domain (RBD) from spike protein (S) antibodies (IgG
    suggested: None
    For vaccinated, partially vaccinated and individuals with previous infection of COVID-19 data on the quantification of IgG (anti-RBD/S) and nAb antibody response activity was represented as an estimated geometric mean (GM) with 95% confidence interval (95% CI).
    anti-RBD/S
    suggested: None
    Software and Algorithms
    SentencesResources
    Assays were performed in serum samples by the SARS-CoV-2 IgG II Quant assay (Abbott Diagnostics, IL, USA).
    Abbott
    suggested: (Abbott, RRID:SCR_010477)

    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:
    Our study has some limitations, the cohort includes only active healthy workers, without severe comorbidities, and all participants are under 70 years old, with over representation of the female population. The occupational risk is reduced, although the majority of the participants manipulate SARS-CoV-2 positive samples, strict guidelines to use individual protective equipment limit the occupational risk exposure being reduced compared to medical personnel with close contact with patients. The heterogeneity in the reference units to quantify the detected antibodies posed a difficulty to compare our data with other studies. Few studies used the same units that we used in this study. This point was already highlighted by Earle et al., [11] that suggested the use of the WHO International Standard (NIBSC 20/136) to express neutralizing antibodies titers in IU/mL and binding antibodies titers in BAU/mL to be possible to compare data among different studies using serology assays, in the context of COVID-19 pandemic. Given the importance to compare different vaccines among different populations to help to design new strategies to battle the pandemic, this point is crucial to a better comprehension of data obtained around the world. We didn’t explore the antibody titers for variants of concern, and a decrease of antibody titers could be expected. The cellular immunity and other immunological mechanisms weren’t explored during the study. In our study, we found a high correlation betwe...

    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.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2021.12.10.21267607v1 on medRxiv