Durability and Cross-Reactivity of Immune Responses Induced by an AS03-Adjuvanted Plant-Based Recombinant Virus-Like Particle Vaccine for COVID-19

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Abstract

As the SARS-COV-2 pandemic evolves, what is expected of vaccines extends beyond efficacy to include consideration of both durability and variant cross-reactivity. This report expands on previously reported immunogenicity results from a Phase 1 trial of an AS03-adjuvanted, plant-based coronavirus-like particle (CoVLP) displaying the spike (S) glycoprotein of the ancestral SARS-CoV-2 virus in healthy adults 18-49 years of age ( NCT04450004 ). When humoral and cellular responses against the ancestral strain were evaluated 6 months post-second dose (D201), 100% of vaccinated individuals retained binding antibodies, and ∼95% retained neutralizing antibodies; interferon gamma (IFN-γ) and interleukin 4 (IL-4) responses directed against the ancestral S protein were also still detectable in ∼94% and ∼92% of vaccinees respectively. Variant-specific, cross-reactive neutralizing antibody (NAb) levels were assessed at D42 and D201 using both live wild-type and pseudovirion assays (Alpha, Beta, Gamma) or the wild-type assay alone (Delta, Omicron). In the wild-type assay, broad cross-reactivity was detected against all variants at D42 (100% Alpha and Delta, 94% Beta and Gamma, 74% Omicron). At D201, cross-reactive antibodies were detectable in almost all participants against Alpha, Gamma and Delta variants (94%) and the Beta variant (83%) and in a smaller proportion against Omicron (44%). Results were similar in the pseudovirion assay (D42, 100% cross-reactivity to Alpha and Gamma variants, 95% to Beta variant, D201, 94% for Alpha, Beta and Gamma variants). These data suggest that two doses of 3.75 µg CoVLP+AS03 elicit a durable and cross-reactive response that persists for at least 6 months post-vaccination.

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  1. SciScore for 10.1101/2021.08.04.21261507: (What is this?)

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

    Table 1: Rigor

    EthicsIRB: Ethical approved was provided by the Advarra Institutional Review Board as well as the Health Products and Food Branch of Health Canada and the study was carried out in accordance with the Declaration of Helsinki and the principles of Good Clinical Practices.
    Consent: Participants were recruited from existing databases of volunteers, and written informed consent was obtained from all study participants before any study procedure.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Standardization of Antibody Titers with the WHO 20/136 Pooled Sera: As previously described 37, WHO International Standard anti-SARS-CoV-2 immunoglobulin (human; NIBSC code: 20/136) was included in antibody binding and neutralization assays for the purpose of facilitating comparison of results with other studies.
    anti-SARS-CoV-2 immunoglobulin
    suggested: None
    Software and Algorithms
    SentencesResources
    GraphPad Prism software was used to calculate means and 95% CIs.
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)

    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: We found the following clinical trial numbers in your paper:

    IdentifierStatusTitle
    NCT04450004Active, not recruitingSafety, Tolerability and Immunogenicinity of a Coronavirus-L…


    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.