Effectiveness of the mRNA BNT162b2 vaccine six months after vaccination: findings from a large Israeli HMO

  1. Jennifer Kertes
  2. Sharon Baruch Gez
  3. Yaki Saciuk
  4. Lia Supino-Rosin
  5. Naama Shamir Stein
  6. Miri Mizrahi-Reuveni
  7. Anat Ekka Zohar

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Abstract

Israel is currently experiencing a new wave of CoVid-19 infection, six months after implementing a national vaccination campaign. We carried out three discrete analyses using data from a large Israeli HMO to determine whether IgG levels of those fully vaccinated drop over time, the relationship between IgG titer and subsequent PCR-confirmed infection, and compare PCR-confirmed infection rates by period of vaccination. We found that mean IgG antibody levels steadily decreased over the six-month period in the total tested population, and in all age groups. An inverse relationship was found between IgG titer and subsequent CoVid-19 infection (PCR-positive). Those participants vaccinated in the first two months of the campaign were more likely to become infected than those subsequently vaccinated. The 60+ vaccinated had lower initial IgG levels, and were at greater risk of infection. The findings support the decision to add a booster vaccine for those aged 60 and over.

Article Summary Line

The BNT162b2 vaccine was found to be less effective in protecting against Covid-19 infection after six months, and vaccination with a third dose is indicated.

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  1. ScreenIT

    SciScore for 10.1101/2021.09.01.21262957: (What is this?)

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

    Table 1: Rigor

    EthicsConsent: The study was approved by the Maccabi Helsinki Committee (#0178-20-MHS), with informed consent waived, as all data extracted from the database were anomized and aggregated.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    IgG antibody testing was carried out using SARS-CoV-2 specific anti-spike antibodies with follow-up chemo-luminescence immunoassay (Quant II IgG anti-Spike CoV2-SARS by Abbott (Illinois, USA)) and reported as AU/ml (Arbitrary units).
    anti-spike
    suggested: None
    Quant II IgG
    suggested: None
    IgG antibody levels of the vaccinated population over time: All HMO members that had received both vaccine doses and had a subsequent IgG test for SARS-CoV-2 antibodies at least seven days after the second vaccination were included in this component of the study.
    SARS-CoV-2
    suggested: None
    Software and Algorithms
    SentencesResources
    All data were extracted from the Maccabi HealthCare Services database.
    Maccabi HealthCare
    suggested: None
    IgG antibody testing was carried out using SARS-CoV-2 specific anti-spike antibodies with follow-up chemo-luminescence immunoassay (Quant II IgG anti-Spike CoV2-SARS by Abbott (Illinois, USA)) and reported as AU/ml (Arbitrary units).
    Abbott
    suggested: (Abbott, RRID:SCR_010477)
    Statistical analyses were carried out using SPSS, version 25 (BMI©) and R (version 3.6.2)
    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 study findings here are subject to a number of limitations. Firstly, serology test findings were not based on repeated tests in the same population, but a description of the results over time of a non-randomly selected population. Those presenting for serology and PCR testing were not a randomly selected group. Mean serology levels were calculated for each sub-population, despite the potential for outlier measures to skew results, to allow statistical comparison between sub-population groups. Numbers were small for some stratified data, particularly for the 120-149 period, and should be interpreted with caution. Study findings were not adjusted for serology test accuracy. Conclusions are made on the assumption that the majority of those infected in the third component of the study (by time of vaccination) were infected with the Delta variant, given its’ prevalence in Israel. Given these limitations, the different elements of the study were based on large numbers of a vaccinated population with six months of follow-up time to measure CoVid-19 infection. We established that serology levels for all groups have decreased over time, that there is a strong relationship between serology levels and subsequent infection, and that those vaccinated early in the vaccination campaign had higher infection rates. These factors taken together suggest that the BNT162b2 vaccine, as indicated by the manufacturer, offers lower protection against infection over time, independent of variant ty...

    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 10.1101/2021.09.01.21262957v1 on medRxiv