Background: The current propagation models of COVID-19 are poorly consistent with existing epidemiological data and with evidence that the SARS-CoV-2 genome is mutating, for potential aggressive evolution of the disease. Objectives: We looked for fundamental variables that were missing from current analyses. Among them were regional climate heterogeneity, viral evolution processes versus founder effects, and large-scale virus containment measures. Methods: We challenged regional versus genetic evolution models of COVID-19 at a whole-population level, over 168,089 laboratory-confirmed SARS-CoV-2 infection cases in Italy, Spain, and Scandinavia at early time-points of the pandemic. Diffusion data in Germany, France, and the United Kingdom provided a validation dataset of 210,239 additional cases. Results: Mean doubling time of COVID-19 cases was 6.63 days in Northern versus 5.38 days in Southern Italy. Spain extended this trend of faster diffusion in Southern Europe, with a doubling time of 4.2 days. Slower doubling times were observed in Sweden (9.4 days), Finland (10.8 days), and Norway (12.95 days). COVID-19 doubling time in Germany (7.0 days), France (7.5 days), and the United Kingdom (7.2 days) supported the North/South gradient model. Clusters of SARS-CoV-2 mutations upon sequential diffusion were not found to clearly correlate with regional distribution dynamics. Conclusion: Acquisition of mutations upon SARS-CoV-2 spreading failed to explain regional diffusion heterogeneity at early pandemic times. Our findings indicate that COVID-19 transmission rates are rather associated with a sharp North/South climate gradient, with faster spreading in Southern regions. Thus, warmer climate conditions may not limit SARS-CoV-2 infectivity. Very cold regions may be better spared by recurrent courses of SARS-CoV-2 infection.
【저자키워드】 COVID-19, pandemic, Mutation rates, spreading dynamics, propagation model, 【초록키워드】 Evolution, SARS-CoV-2, Europe, Mutation, SARS-COV-2 infection, Genetic, Italy, virus, heterogeneity, Region, Germany, viral evolution, Spain, France, dataset, epidemiological data, SARS-CoV-2 mutation, distribution, United Kingdom, Norway, Evidence, COVID-19 transmission, containment measures, COVID-19 case, laboratory-confirmed SARS-CoV-2 infection, doubling, diffusion, variable, regions, Effects, limit, Course, the disease, provided, supported, condition, faster, analyses, explain, early time-point, the SARS-CoV-2 genome, 【제목키워드】 Dynamics, Region, Climate, spreading, drift,