A systematic review of the impact of the Alpha and Gamma variants of concern on hospitalization and symptomatic rates of SARS-CoV-2

  1. Alexandra Schroeder
  2. Matthew R. MacLeod

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Abstract

The hospitalization and symptomatic rates of Severe Acute Respiratory Syndrome Coronavirus Disease 2019 (SARS-CoV-2) are key epidemiological parameters affecting risk analyses conducted for the Canadian Armed Forces (CAF) during the Coronavirus Disease-19 (COVID-19) pandemic. As one of the criteria of a variant of concern (VOC) is that it affects disease severity, the authors sought to understand whether the Alpha and Gamma VOCs are significantly different in these two parameters than the original wildtype of SARS-CoV-2, the most prevalent in relevant areas of Canada as of study initiation. Searches for studies were conducted in Scopus and PubMed, and located through following citations and receiving studies from daily literature scans. For the hospitalization outcome, effect ratios relative to original wildtype were included. For the symptomatic ratio, the ratio itself for each variant was used. Analysis of age-related effects was of particular value, as CAF members are primarily adults under the age of 60. The firmest conclusion of this review is that the Alpha VOC comes with a higher relative risk of hospitalization compared to the original wildtype, most likely above 1.4, while unlikely to be above 2, with the balance of evidence being that the relative risk is not significantly modified by age. The evidence for Gamma is more limited, but the odds ratio may be above 2, and potentially much greater than that, especially for those 20-39 years of age. For both VOCs reports on symptomatic ratio differed on whether there was an effect, as well as its potential direction.

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  1. ScreenIT

    SciScore for 10.1101/2021.08.13.21261151: (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

    Software and Algorithms
    SentencesResources
    The primary search was conducted on Scopus (12) and PubMed (13) on 21 May 2021.
    PubMed
    suggested: (PubMed, RRID:SCR_004846)
    The preferred summary measure of interest for hospitalization was the risk ratio of the variant (Alpha or Gamma) compared to that of the original wildtype; where this was not available, odds ratio or hazard ratio was used.
    Gamma
    suggested: (GAMMA, RRID:SCR_009484)

    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 primary limitation of this review was the paucity of studies of the Gamma VOC. The inconsistency of reported symptomatic ratios for VOCs and the wildtype, where they were included, makes it difficult to draw any firm conclusions; at least some of this is due to the many different methods for collecting reports of symptoms and which symptoms are or are not included. The firmest conclusion that can be drawn from this review is that the Alpha variant comes with a higher relative risk of hospitalization compared to the original wildtype, most likely above 1.4, while unlikely to be above 2, with the balance of evidence being that the relative risk is not significantly modified by age – suggesting that general estimates of relative risk for this variant are acceptable. The evidence for Gamma is more limited, but the odds ratio may be above 2, and potentially much greater than that, especially for those 20-39 years of age (23). In the Canadian context, the increased transmissibility of the Delta variant compared to both Alpha and Gamma (4), has it rapidly becoming the dominant variant country-wide (26). Therefore, further research on Alpha and Gamma may be less relevant to policy-makers, except to the extent that future research on the virulence of Delta may compare it to Alpha or other variants with which it is co-circulating, rather than to the original wildtype. That said, one of the studies cited here compares the hospitalization rate of Delta to the original wildtype (20); ...

    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

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  2. Version published to 10.1101/2021.08.13.21261151v1 on medRxiv