Country-level determinants of the severity of the first global wave of the COVID-19 pandemic: an ecological study

  1. Tiberiu A Pana
  2. Sohinee Bhattacharya
  3. David T Gamble
  4. Zahra Pasdar
  5. Weronika A Szlachetka
  6. Jesus A Perdomo-Lampignano
  7. Kai D Ewers
  8. David J McLernon
  9. Phyo K Myint

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Abstract

We aimed to identify the country-level determinants of the severity of the first wave of the COVID-19 pandemic.

Design

Ecological study of publicly available data. Countries reporting >25 COVID-19 related deaths until 8 June 2020 were included. The outcome was log mean mortality rate from COVID-19, an estimate of the country-level daily increase in reported deaths during the ascending phase of the epidemic curve. Potential determinants assessed were most recently published demographic parameters (population and population density, percentage population living in urban areas, population >65 years, average body mass index and smoking prevalence); economic parameters (gross domestic product per capita); environmental parameters (pollution levels and mean temperature (January–May); comorbidities (prevalence of diabetes, hypertension and cancer); health system parameters (WHO Health Index and hospital beds per 10 000 population); international arrivals; the stringency index, as a measure of country-level response to COVID-19; BCG vaccination coverage; UV radiation exposure; and testing capacity. Multivariable linear regression was used to analyse the data.

Primary outcome

Country-level mean mortality rate: the mean slope of the COVID-19 mortality curve during its ascending phase.

Participants

Thirty-seven countries were included: Algeria, Argentina, Austria, Belgium, Brazil, Canada, Chile, Colombia, the Dominican Republic, Ecuador, Egypt, Finland, France, Germany, Hungary, India, Indonesia, Ireland, Italy, Japan, Mexico, the Netherlands, Peru, the Philippines, Poland, Portugal, Romania, the Russian Federation, Saudi Arabia, South Africa, Spain, Sweden, Switzerland, Turkey, Ukraine, the UK and the USA.

Results

Of all country-level determinants included in the multivariable model, total number of international arrivals (beta 0.033 (95% CI 0.012 to 0.054)) and BCG vaccination coverage (−0.018 (95% CI −0.034 to –0.002)), were significantly associated with the natural logarithm of the mean death rate.

Conclusions

International travel was directly associated with the mortality slope and thus potentially the spread of COVID-19. Very early restrictions on international travel should be considered to control COVID-19 outbreaks and prevent related deaths.

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  1. Version published to 10.1136/bmjopen-2020-042034
  2. Version published to 10.1101/2020.05.13.20100677v3 on medRxiv
  3. Version published to 10.1101/2020.05.13.20100677v2 on medRxiv
  4. ScreenIT

    SciScore for 10.1101/2020.05.13.20100677: (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

    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:
    While the BCG vaccine has been postulated to exhibit non-specific immunomodulatory properties, which may reduce SARS-CoV-2 viraemia after exposure,43 current epidemiological evidence is derived from ecological studies45 and needs to be interpreted in the light of the inherent limitations of this study design. Further ongoing studies (NCT0432720646, NCT0432844147) may provide more robust evidence regarding the association between BCG vaccination and COVID-19. Our analyses also revealed a few surprising findings: the intensity of COVID-19 testing was apparently associated with mean mortality rate increases while the country-level prevalence of hypertension was apparently associated with mean mortality rate decreases. These findings appear to be contradictory to previous evidence suggesting that testing intensity may be associated with decreased COVID-19 mortality,48 while hypertension was clearly associated with increased mortality.49 These surprising findings need to be interpreted in the light of our ecological study design in which residual confounders may influence these associations. Strengths and Limitations: The main strength of this study lies in its use of comparable and relevant outcome data derived from contemporary death reporting from countries affected by COVID-19. As testing rates for the virus vary across countries, the incidence or prevalence of the disease cannot be compared between countries. While death from the disease is a hard outcome, the denominator inf...

    Results from TrialIdentifier: We found the following clinical trial numbers in your paper:

    IdentifierStatusTitle
    NCT0432720646Trial number did not resolve on clinicaltrials.gov. Is the number correct?NA
    NCT0432844147Trial number did not resolve on clinicaltrials.gov. Is the number correct?NA

    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.

  5. Version published to 10.1101/2020.05.13.20100677v1 on medRxiv