Facing the Omicron variant – How well do vaccines protect against mild and severe COVID-19? Third interim analysis of a living systematic review

  1. Wiebe Külper-Schiek
  2. Vanessa Piechotta
  3. Antonia Pilic
  4. Madeleine Batke
  5. Léa-Sophie Dreveton
  6. Brogan Geurts
  7. Judith Koch
  8. Stefan Köppe
  9. Marina Treskova
  10. Sabine Vygen-Bonnet
  11. Maria Waize
  12. Ole Wichmann
  13. Thomas Harder

Reviewed by

Read the full article See related articles

Listed in

Log in to save this article

Abstract

Background

The SARS-CoV-2 Omicron variant is currently the dominant variant globally. This 3 rd interim analysis of a living systematic review summarizes evidence on COVID-19 vaccine effectiveness (VE) and duration of protection against Omicron.

Methods

We systematically searched the COVID-19 literature for controlled studies evaluating the effectiveness of COVID-19 vaccines approved in the European Union up to 14/01/2022, complemented by hand-searches of websites and metasearch engines up to 11/02/2022. We considered the following comparisons: full primary immunization vs. no vaccination; booster immunization vs. no vaccination; booster vs. primary immunization. VE against any confirmed SARS-CoV-2 infection, symptomatic, and severe COVID-19 (i.e. COVID-19-related hospitalization, ICU-admission, or death) was indicated providing estimate ranges. Meta-analysis was not performed due to high study heterogeneity. Risk of bias was assessed with ROBINS-I, certainty of evidence evaluated using GRADE.

Results

We identified 26 studies, including 430 to 2.2 million participants.

VE against any confirmed SARS-CoV-2 infection compared to no vaccination ranged between 0-62% after full primary immunization, and between 34-66% after a booster dose. VE-range for booster vs. primary immunization was 34-54.6%.

Against symptomatic COVID-19, VE ranged between 6-76% after full primary immunization, and between 19-73.9% after booster immunization, if compared to no vaccination. When comparing booster vs. primary immunization VE ranged between 56-69%.

VE against severe COVID-19 compared to no vaccination ranged between 3-84% after full primary immunization, and between 12-100% after a booster dose. One study compared booster vs. primary immunization (VE 100%, 95% CI 71.4-100).

VE was characterized by a moderate to strong decline within three to six months for SARS-CoV-2 infections and symptomatic COVID-19. Against severe COVID-19 protection remained robust at least for up to six months. Waning immunity was more profound after primary than booster immunization.

Risk of bias was moderate to critical across studies and outcomes. GRADE-certainty was very low for all outcomes.

Author’s conclusions

Under the Omicron variant, effectiveness of EU-licensed COVID-19 vaccines in preventing any SARS-CoV-2 infection or mild disease is low and only short-lasting after primary immunization, but can be improved by booster vaccination. VE against severe COVID-19 remains high and is long-lasting, especially after receiving the booster vaccination.

Article activity feed

  1. ScreenIT

    SciScore for 10.1101/2022.05.25.22275516: (What is this?)

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

    Table 1: Rigor

    Ethicsnot detected.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    No key resources detected.

    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:
    Additional data limitations stem from the fact that VE estimates for more than one vaccine were reported.

    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.
    • Thank you for including a protocol registration statement.

    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 10.1101/2022.05.25.22275516v1 on medRxiv