Effect of booster vaccination against Delta and Omicron SARS-CoV-2 variants in Iceland

  1. Gudmundur L. Norddahl
  2. Pall Melsted
  3. Kristbjorg Gunnarsdottir
  4. Gisli H. Halldorsson
  5. Thorunn A. Olafsdottir
  6. Arnaldur Gylfason
  7. Mar Kristjansson
  8. Olafur T. Magnusson
  9. Patrick Sulem
  10. Daniel F. Gudbjartsson
  11. Unnur Thorsteinsdottir
  12. Ingileif Jonsdottir
  13. Kari Stefansson

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Abstract

By the end of July 2021, the majority of the Icelandic population had received vaccination against COVID-19. In mid-July a wave of SARS-CoV-2 infections, dominated by the Delta variant, spread through the population, followed by an Omicron wave in December. A booster vaccination campaign was initiated to curb the spread of the virus. We estimate the risk of infection for different vaccine combinations using vaccination data from 276,028 persons and 963,557 qPCR tests for 277,687 persons. We measure anti-Spike-RBD antibody levels and ACE2-Spike binding inhibitory activity in 371 persons who received one of four recommended vaccination schedules with or without an mRNA vaccine booster. Overall, we find different antibody levels and inhibitory activity in recommended vaccination schedules, reflected in the observed risk of SARS-CoV-2 infections. We observe an increased protection following mRNA boosters, against both Omicron and Delta variant infections, although BNT162b2 boosters provide greater protection against Omicron than mRNA-1273 boosters.

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  1. Version published to 10.1038/s41467-022-33076-4
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    SciScore for 10.1101/2022.02.26.22271509: (What is this?)

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

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    Table 2: Resources

    Antibodies
    SentencesResources
    Antibody measurement: Pan-Ig antibody levels against SARS-CoV-2 Spike-RBD in serum samples was quantified using Elecsys anti-SARS-CoV-2 S (Roche Diagnostics
    anti-SARS-CoV-2 S
    suggested: None

    Results from OddPub: Thank you for sharing your data.

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    The observational nature of the population study presents limitations to consider. There is a confounding factor between age and time of vaccination, namely the first to receive vaccination were front-line workers and the elderly. Further, the vaccine received correlates with age and gender. For the analyses of booster vaccinations the group sizes differ, which is accounted for in the statistical analysis but selection bias could generate statistical artifacts. The key strength of this study is the complete nationwide coverage, in terms of the high fraction of the population vaccinated, the sheer number of PCR tests conducted and sequencing of viral isolates. The mixed vaccination approach in Iceland provided a unique opportunity to investigate the effects of various vaccination schedules and booster combinations within a single population. Our data clearly demonstrate and confirm the major benefit of mRNA booster vaccinations against SARS-CoV-2 infections, both against the delta and omicron VOCs, regardless of the vaccine type given in the primary series. We observe a great increase in antibody level and inhibitory activity, consistent with our estimates of the effectiveness of protection against SARS-CoV-2 infections by mRNA booster vaccinations at a population level.

    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.

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  3. Version published to 10.1101/2022.02.26.22271509 on medRxiv