EGU21-8955, updated on 25 Sep 2023
EGU General Assembly 2021
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Analysis of the potential drivers of seasonality in COVID-19 transmission dynamics in 409 locations across 26 countries

Rachel Lowe1, Ben Armstrong1, Sam Abbott1, Sophie Meakin1, Kathleen O'Reilly1, Rosa Von Borries2, Rochelle Schneider1, Dominic Roye3, Masahiro Hashizume4, Mathilde Pascal5, Aurelio Tobias6, Ana Maria Vicedo-Cabrera7, Antonio Gasparrini1, Francesco Sera8, and the MCC Network & CMMID COVID-19 working group*
Rachel Lowe et al.
  • 1London School of Hygiene & Tropical Medicine, Infectious Disease Epidemiology, London, United Kingdom of Great Britain – England, Scotland, Wales (
  • 2Charité Universitätsmedizin, Berlin, Germany
  • 3University of Santiago de Compostela, Universidade de Santiago de Compostela, Spain
  • 4Department of Global Health Policy, Graduate School of Medicine, The University of Tokyo, Japan
  • 5Santé Publique France, France
  • 6Institute of Environmental Assessment and Water Research, Spanish Council for Scientific Research, Barcelona, Spain
  • 7Universität Bern, Bern, Switzerland
  • 8Department of Statistics, Computer Science and Applications "G. Parenti", University of Florence, Florence, Italy
  • *A full list of authors appears at the end of the abstract

More than a year since its emergence, there is conflicting evidence on the potential influence of weather conditions on SARS-CoV-2 transmission dynamics. We used a two-stage ecological modelling approach to estimate weather-dependent signatures in SARS-CoV-2 transmission in the early phase of the pandemic, using a dataset of 3 million COVID-19 cases reported until 31 May 2020, spanning 409 locations in 26 countries. We calculated the effective reproduction number (Re) over a location-specific early-phase time-window of 10-20 days, for which local transmission had been established but before non-pharmaceutical  interventions had become established as measured by the OxCGRT Government Response Index. We calculated mean levels of meteorological factors, including temperature and humidity observed in the same time window used to calculate Re.  Using a multilevel meta-regression approach, we modelled nonlinear effects of meteorological factors,  while accounting for government interventions and socio-demographic factors. A weak non-monotonic association between temperature, absolute humidity and Re was identified, with a decrease in Re of 0.087 (95% CI: 0.025; 0.148) between mean temperature of 10.2°C (maximum) and 20°C (minimum) and a decrease in Re of 0.061 (95% CI: 0.011; 0.111) between absolute humidity of 6.6 g/m3 (maximum) and 11 g/m3 (minimum). However, government interventions explained twice as much of the variation in Re compared meteorological factors. We find little evidence of meteorological conditions having influenced the early stages of local epidemics, and conclude that population behaviour and governmental intervention are more important drivers of transmission.

MCC Network & CMMID COVID-19 working group:

MCC Network: Wenbiau Hu, Shilu Tong, Eric Lavigne, Patricia Matus Correa, Xia Meng, Haidong Kan, Dominic Roye, Jan Kynčl, Aleš Urban,Hans Orru, Niilo Ryti, Simon Cauchemez, Marco Dallavalle, Alexandra Schneider, Ariana Zeka, Yasushi Honda, Chris Fook Sheng Ng, Barrak Alahmad, Shilpa Rao , Francesco Di Ruscio, Gabriel Carrasco, Xerxes Seposo, Iulian Horia Holobâc, Ho Kim, Whanhee Lee, Carmen Íñiguez, Martina S. Ragettli , Alicia Aleman, Valentina Colistro, Michelle Bell, Antonella Zanobetti, Joel Schwartz, Tran Ngoc Dang, Noah Scovronick, Micheline de Sousa Zanotti Stagliorio Coélho, Magali Hurtado Diaz. CMMID COVID-19 working group: Timothy W Russell, Mihaly Koltai, Adam J Kucharski, Rosanna C Barnard, Matthew Quaife, Christopher I Jarvis, Jiayao Lei, James D Munday, Yung-Wai Desmond Chan, Billy J Quilty, Rosalind M Eggo, Stefan Flasche, Anna M Foss, Samuel Clifford, Damien C Tully, W John Edmunds, Petra Klepac, Oliver Brady, Fabienne Krauer, Simon R Procter, Thibaut Jombart, Alicia Rosello, Alicia Showering, Sebastian Funk, Joel Hellewell, Fiona Yueqian Sun, Akira Endo, Jack Williams, Amy Gimma, Naomi R Waterlow, Kiesha Prem, Nikos I Bosse , Hamish P Gibbs, Katherine E. Atkins, Carl A B Pearson, Yalda Jafari, C Julian Villabona-Arenas, Mark Jit, Emily S Nightingale, Nicholas G. Davies, Kevin van Zandvoort, Yang Liu, Frank G Sandmann, William Waites, Kaja Abbas, Graham Medley, Gwenan M Knight.

How to cite: Lowe, R., Armstrong, B., Abbott, S., Meakin, S., O'Reilly, K., Von Borries, R., Schneider, R., Roye, D., Hashizume, M., Pascal, M., Tobias, A., Vicedo-Cabrera, A. M., Gasparrini, A., and Sera, F. and the MCC Network & CMMID COVID-19 working group: Analysis of the potential drivers of seasonality in COVID-19 transmission dynamics in 409 locations across 26 countries, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8955,, 2021.

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