Evaluation of the combined effect of mobility and seasonality on the COVID-19 pandemic: a Lombardy-based study

Evaluation of the combined effect of mobility and seasonality on the COVID-19 pandemic: a Lombardy-based study


  • Yuri Matteo Falzone a:1:{s:5:"en_US";s:72:"1. Neurology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy";}
  • Luca Bosco
  • Giacomo Sferruzza
  • Tommaso Russo
  • Marco Vabanesi
  • Carlo Signorelli
  • Massimo Filippi


SARS-CoV2, UV, environmental factors, transmissibility, GAM analysis


Restrictions to human mobility had a significant role in limiting SARS-CoV-2 spread. It has been suggested that seasonality might affect viral transmissibility. Our study retrospectively investigates the combined effect that seasonal environmental factors and human mobility played on transmissibility of SARS-CoV-2 in Lombardy, Italy, in 2020.

Environmental data were collected from accredited open-source web services. Aggregated mobility data for different points of interests were collected from Google Community Reports. The Reproduction number (Rt), based on the weekly counts of confirmed symptomatic COVID-19, non-imported cases, was used as a proxy for SARS-CoV-2 transmissibility. Assuming a non-linear correlation between selected variables, we used a Generalized Additive Model (GAM) to investigate with univariate and multivariate analyses the association between seasonal environmental factors (UV-index, temperature, humidity, and atmospheric pressure), location-specific mobility indices, and Rt.

UV-index was the most effective environmental variable in predicting Rt. An optimal two-week lag-effect between changes in explanatory variables and Rt was selected. The association between Rt variations and individually taken mobility indices differed: Grocery & Pharmacy, Transit Station and Workplaces displayed the best performances in predicting Rt when individually added to the multivariate model together with UV-index, accounting for 85.0%, 85.5% and 82.6% of Rt variance, respectively. According to our results, both seasonality and social interaction policies played a significant role in curbing the pandemic. Non-linear models including UV-index and location-specific mobility indices can predict a considerable amount of SARS-CoV-2 transmissibility in Lombardy during 2020, emphasizing the importance of social distancing policies to keep viral transmissibility under control, especially during colder months.


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How to Cite

Falzone YM, Bosco L, Sferruzza G, Russo T, Vabanesi M, Signorelli C, et al. Evaluation of the combined effect of mobility and seasonality on the COVID-19 pandemic: a Lombardy-based study. Acta Biomed [Internet]. 2022 Aug. 31 [cited 2024 Jul. 22];93(4):e2022212. Available from: https://www.mattioli1885journals.com/index.php/actabiomedica/article/view/12645