Prevalence of anti-platelet factor4/polyanionic antibodies after COVID-19 vaccination with ChAdOx1 nCoV-19 and CoronaVac in Thais

  1. Phichchapha Noikongdee
  2. Pornnapa Police
  3. Tichayapa Phojanasenee
  4. Pichika Chantrathammachart
  5. Pimjai Niparuck
  6. Teeraya Puavilai
  7. Angsana Phuphuakrat
  8. Pantep Angchaisuksiri
  9. Kochawan Boonyawat

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Abstract

Introduction

Vaccine-induced thrombotic thrombocytopenia (VITT) has been reported after vaccination with the adenoviral vector COVID-19 vaccine ChAdOx1 nCoV-19 in European countries. To date, no case of VITT has been reported in Thais after COVID-19 vaccination. We determined the frequency of anti-PF4/polyanionic antibodies in the Thai population receiving the COVID-19 vaccines.

Methods

We conducted a cross-sectional study to evaluate the prevalence of anti-PF4/polyanionic antibodies in health care workers who received COVID-19 vaccination with ChAdOx1 nCoV-19 or CoronaVac within 7-35 days. A control population who had not been vaccinated was also included. Anti-PF4/polyanionic antibodies were detected using enzyme-link immunosorbent assay (ELISA). Functional assay with platelet aggregation was performed for all positive anti-PF4/polyanionic antibody ELISA tests.

Results

A total of 646 participants were included in the study. 221 received ChAdOx1 nCoV-19, 232 received CoronaVac, and 193 participants were in the control group. The prevalence of anti-PF4 antibodies was 2.3% (95% confidence interval [CI] 0.7 to 5.2), 1.7% (95% CI, 0.5 to 4.4) in the ChAdOx1 nCoV-19 and CoronaVac groups, respectively. There was no positive test in the control group. None of the PF4/polyanionic positive sera induced platelet aggregation.

Conclusion

We found a low prevalence of anti-PF4 antibodies in Thais after vaccination with ChAdOx1 nCoV-19 and CoronaVac. Low titer positive PF4/polyanionic ELISA results should be interpreted with caution when screening asymptomatic individuals after vaccination against COVID-19.

Highlights

  • High titer PF4/polyanion antibodies are associated with vaccine-induced immune thrombotic thrombocytopenia (VITT).

  • Low titer PF4/polyanion antibodies occur after vaccination with ChAdOx1 nCoV-19 and CoronaVac in some vaccinees.

  • These PF4/polyanion antibodies do not activate platelets and lack of association with VITT.

  • Low-titer positive PF4/polyanionic ELISA results should be interpreted with caution when screening asymptomatic individuals after vaccination against COVID-19.

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  1. ScreenIT

    SciScore for 10.1101/2021.07.15.21260622: (What is this?)

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

    Table 1: Rigor

    EthicsConsent: All participants gave written informed consent.
    IRB: The study protocol was approved by the Human Research Ethics Committee of the Faculty of Medicine at Ramathibodi Hospital, Mahidol University.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Anti-PF4/polyanionic antibodies were screened by IgG-specific ELISA (Hyphen Biomed Zymutest HIA IgG, Quadratech Diagnostics, UK) according to the manufacturer’s instructions.
    Anti-PF4/polyanionic
    suggested: None
    Software and Algorithms
    SentencesResources
    All statical analyses were performed on GraphPad Prism 9.1.1 (GraphPad Software, CA, USA) and Stata statistical software version 15.1 (StataCorp, TX, 2018).
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)
    GraphPad
    suggested: (GraphPad Prism, RRID:SCR_002798)
    Stata statistical
    suggested: None
    StataCorp
    suggested: (Stata, RRID:SCR_012763)

    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: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    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.

  2. Version published to 10.1101/2021.07.15.21260622v1 on medRxiv