Trends of SARS-Cov-2 infection in 67 countries: Role of climate zone, temperature, humidity and curve behavior of cumulative frequency on duplication time

  1. Jaime Berumen
  2. Max Schmulson
  3. Guadalupe Guerrero
  4. Elizabeth Barrera
  5. Jorge Larriva-Sahd
  6. Gustavo Olaiz
  7. Rebeca Garcia-Leyva
  8. Rosa María Wong Chew
  9. Miguel Betancourt-Cravioto
  10. Héctor Gallardo
  11. Germán Fajardo-Dolci
  12. Roberto Tapia-Conyer

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Abstract

Objective

To analyze the role of temperature, humidity, date of first case diagnosed (DFC) and the behavior of the growth-curve of cumulative frequency (CF) [number of days to rise (DCS) and reach the first 100 cases (D100), and the difference between them (ΔDD)] with the doubling time (Td) of Covid-19 cases in 67 countries grouped by climate zone.

Design

Retrospective incident case study.

Setting

WHO based register of cumulative incidence of Covid-19 cases.

Participants

1,706,914 subjects diagnosed between 12-29-2019 and 4-15-2020.

Exposures

SARS-Cov-2 virus, ambient humidity, temperature and climate areas (temperate, tropical/subtropical).

Main outcome measures

Comparison of DCS, D100, ΔDD, DFC, humidity, temperature, Td for the first (Td10) and second (Td20) ten days of the CF growth-curve between countries according to climate zone, and identification of factors involved in Td, as well as predictors of CF using lineal regression models.

Results

Td10 and Td20 were ≥3 days longer in tropical/subtropical vs. temperate areas (2.8±1.2 vs. 5.7±3.4; p=1.41E-05 and 4.6±1.8 vs. 8.6±4.2; p=9.7E-05, respectively). The factors involved in Td10 (DFC and ΔDD) were different than those in Td20 (Td10 and climate areas). After D100, the fastest growth-curves during the first 10 days, were associated with Td10<2 and Td10<3 in temperate and tropical/subtropical countries, respectively. The fold change Td20/Td10 >2 was associated with earlier flattening of the growth-curve. In multivariate models, Td10, DFC and ambient temperature were negatively related with CF and explained 44.7% (r 2 = 0.447) of CF variability at day 20 of the growth-curve, while Td20 and DFC were negatively related with CF and explained 63.8% (r 2 = 0.638) of CF variability towards day 30 of the growth-curve.

Conclusions

The larger Td in tropical/subtropical countries is positively related to DFC and temperature. Td and environmental factors explain 64% of CF variability in the best of cases. Therefore, other factors, such as pandemic containment measures, would explain the remaining variability.

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  1. ScreenIT

    SciScore for 10.1101/2020.04.18.20070920: (What is this?)

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

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    17 Calculation of doubling time and the parameters of the growth curve of CF of Covid-19 cases: The CF of Covid-19 cases of each country was plotted in Excel and the exponential equation was obtained.
    Excel
    suggested: None
    A post hoc power analysis was performed for each linear regression model using the software G * Power 3.1.9.2, considering the sample size, the β and an α = 0.05.
    G * Power
    suggested: (G*Power, RRID:SCR_013726)
    The statistical analyses were conducted using SPSS version 20 software (SPSS Inc., Chicago, IL, USA).
    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: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    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.

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  2. Version published to 10.1101/2020.04.18.20070920 on medRxiv
  3. Version published to 10.18103/mra.v8i9.2230