COVID-19 Related Mortality: Is the BCG Vaccine Truly Effective?

  1. Jan A. Paredes
  2. Valeria Garduño
  3. Julian Torres

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Abstract

The coronavirus disease 2019 (COVID-19) pandemic has become a worldwide emergency. In the attempt to search for interventions that would improve outcomes, some studies have looked at the potential benefit of BCG vaccination. These past studies have found a statistically significant reduction in COVID-19 related mortality in countries with a current universal bacille Calmette-Guérin (BCG) vaccination policy. However, just as the authors themselves noted, the nature of ecological studies make them very prone to the presence of several confounders. This paper took into account demographic differences, economic differences and the different stages of the pandemic in each country; gathering data from publicly available sources. It was found that no statistically significant difference exists in mortality rates between countries with a current or prior BCG vaccination policy when compared to those that never had such a program. Nevertheless, the immunostimulatory potential of the BCG vaccine might still prove useful in the development of future vaccines or other prophylactic measures.

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  1. ScreenIT

    SciScore for 10.1101/2020.05.01.20087411: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    3 Data on the total population, percentage of the population over 65 years old and the GDP income was retrieved from The World Bank Data Website.19 Data on BCG vaccination policies was retrieved from The BCG World Atlas.20 The IBM SPSS program was then used to analyze statistical data.
    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:
    There are some limitations to be considered in this study. Although great care was taken to try to avoid as many confounders as possible, some still remain. The difference in mortality seems to be higher in the male population than in the female population, which could affect the overall mortality in countries with differing gender compositions.33 Also, some populations are more genetically susceptible to certain diseases and complications than others (e.g. Latin Americans and diabetes).34 Some researchers are looking into this by analyzing genetic differences in the expression of the ACE2 receptor or the CCL2 and MBL genes, which could affect susceptibility to SARS-CoV-2.6, 35, 36 Finally, each country’s response to the outbreak affects subsequent policies taken by other countries and although the coverage of countries currently using BCG was over 90% no data was available for countries with prior vaccination programs.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.

    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 10.1101/2020.05.01.20087411v2 on medRxiv
  3. Version published to 10.1101/2020.05.01.20087411v1 on medRxiv