Interaction between malarial transmission and BCG vaccination with COVID-19 incidence in the world map: A cross-sectional study

  1. Rudra Prosad Goswami
  2. Dheeraj Mittal
  3. Rama Prosad Goswami

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Abstract

Background

COVID-19 (Corona virus Disease-2019) is a new public health emergency and is a pandemic currently. Incidence and mortality of COVID-19 vary in different geographical areas. In this study we aimed to analyse the relationship between malaria transmission and BCG vaccination with COVID-19 incidence in the world map.

Materials and methods

We collected malaria cases data (World Health Organisation (WHO), 2018), worldwide COVID-19 cases and mortality data (European Centre for Disease Prevention and Control) and data on BCG vaccination. COVID-19 incidence and mortality was compared.

Findings

Data on 5316978938 persons from 166 countries were analysed. Malaria incidence rate was negatively correlated with COVID-19 incidence rate (correlation coefficient = -0.513, p<0.001). Malaria free countries had significantly higher number of COVID-19 cases compared to malaria endemic countries. In Europe and Americas, countries, which have higher BCG vaccination coverage, had significantly less mortality per thousand population compared to those with low BCG coverage (median 0.0002 (0-0.0005) vs 0.0029 (0.0002-0.0177), p=0.017). The case fatality ratio of COVID-19 was related nonlinearly to the malaria incidence.

Conclusions

The results suggest the changing human immune system as we progress to eliminate parasitic diseases with time. Chloroquine exposure in malaria endemic zones might have a protective effect.

Summary box

“What is already known on this subject?”

To the best of the authors no similar evidence, of the effect of malarial transmission on the COVID-19 global distribution is known. The effect of the Bacille Calmette Guérin (BCG) vaccine on modifying the human immune system has been reported before and is postulated to protective against certain viral infections like Influenza A (H1N1) and herpes virus.

“What this study adds?”

This study finds that COVID-19 incidence, worldwide is less in countries, which are malaria-endemic. In the European and American countries, increased BCG coverage may have some mortality advantage against COVID-19. The case fatality rate was related to malaria incidence, however, in a complex way. This could be a window into the changing landscape of human immune system as we progress to eliminate parasitic disease with time or this could be due to long-term protective body level of anti-malarials like chloroquine or hydroxychloroquine in countries with higher malaria incidence rate.

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  1. ScreenIT

    SciScore for 10.1101/2020.04.03.20052563: (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
    All data were compiled on an excel sheet and then transferred to SPSS ver. 21.
    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 in this study. Many other parasitic diseases could have been screened, which however due to lack of worldwide data could not be done. Many factors like underreporting of cases might underwhelm this report. Socioeconomics is an important factor, which is missing from the current analysis. To summarize, malaria free countries, worldwide, are experiencing higher burden of COVID-19 pandemic. Among the western countries, those, which have continued high BCG vaccination coverage, have an apparent mortality benefit from COVID-19 infection. However, among the African, Asian and Australasian countries, continued high-level BCG vaccination was associated with increased incidence of and mortality from the COVID-19 infection. From the COVID-19 case fatality analysis a lower mortality could be expected in malaria-endemic countries.

    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 10.1101/2020.04.03.20052563v1 on medRxiv