Quantitative detection of SARS-CoV-2 Omicron BA.1 and BA.2 variants in wastewater through allele-specific RT-qPCR

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Abstract

On November 26, 2021, the World Health Organisation classified the B.1.1.529 SARS-CoV-2 variant as the Omicron variant of concern (VOC). Reports of higher transmissibility and potential immune evasion triggered flight bans and heightened health control measures across the world to stem its distribution. Wastewater-based surveillance has demonstrated to be a useful complement for community-based tracking of SARS-CoV-2 variants. Using design principles of our previous assays that detect VOCs (Alpha and Delta), here we report three allele-specific RT-qPCR assays that can quantitatively detect and discriminate the Omicron BA.1 and BA.2 variants in wastewater. The first assay targets the nine-nucleotide deletion at the L24-A27S of the spike protein for detection of BA.2. The second targets the six-nucleotide deletion at 69-70 of the spike protein for detection of the Omicron BA.1 variant, and the third targets the stretch of mutations from Q493R to Q498R for simultaneous detection of both Omicron BA.1 and BA.2. This method is open-sourced, can be implemented using commercially available RT-qPCR protocols, and would be an important tool for tracking the introduction and spread of the Omicron variants BA.1 and BA.2 in communities for informed public health responses.

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  1. SciScore for 10.1101/2021.12.21.21268077: (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:
    This, however, constitutes a caveat for this work. Assays for the Omicron variant were validated on synthetic DNA carrying WT and Omicron sequences, and against synthetic WT SARS-CoV-2 RNA but not Omicron variant RNA. Further, these assays have not yet been validated against Omicron sequences in real wastewater samples. However, given the rapid increase in circulation of the Omicron VOC, we are sharing these assays and their initial validations for the benefit of the wider wastewater surveillance community. Detailed analytical validation against the Omicron variant RNA will be performed and reported as an update to this preprint.

    Results from TrialIdentifier: No clinical trial numbers were referenced.


    Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).


    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.