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Effects of Environmental Factors on Severity and Mortality of COVID-19

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Domagoj Kifer, Dario Bugada, Judit Villar-Garcia, Ivan Gudelj, Cristina Menni, Carole Sudre, Frano Vučković, Ivo Ugrina, Luca F. Lorini, Margarita Posso, Silvia Bettinelli, Nicola Ughi, Alessandro Maloberti, Oscar Epis, Cristina Giannattasio, Claudio Rossetti, Livije Kalogjera, Jasminka Peršec, Luke Ollivere, Benjamin J. Ollivere & 31 more Huadong Yan, Ting Cai, Guruprasad P. Aithal, Claire J. Steves, Anu Kantele, Mikael Kajova, Olli Vapalahti, Antti Sajantila, Rafal Wojtowicz, Waldemar Wierzba, Zbigniew Krol, Artur Zaczynski, Katarina Zycinska, Marek Postula, Ivica Lukšić, Rok Čivljak, Alemka Markotić, Johannes Brachmann, Andreas Markl, Christian Mahnkopf, Benjamin Murray, Sebastien Ourselin, Ana M. Valdes, Juan P. Horcajada, Xavier Castells, Julio Pascual, Massimo Allegri, Dragan Primorac, Tim D. Spector, Clara Barrios, Gordan Lauc

Original languageEnglish
Article number607786
JournalFrontiers in Medicine
Published20 Jan 2021

Bibliographical note

Funding Information: We would like to thank all anaesthesiologists and nurses in the emergency and intensive care unit, as well as all the people who worked at ASST Papa Giovanni XXIII during the COVID-19 pandemic in Bergamo for their invaluable and brave efforts toward patient's care. We also want to acknowledge the ROCCO Project (Registry of Coronavirus Complications) who helped with scientific support and Dr. A. Bonetalli (Epidemiology Office, ASST Papa Giovanni XXIII, Bergamo, Italy) for her help with data collection. We thank all the medical professionals, nurses, and technicians of the ASST GOM Niguarda Hospital who worked hard during the COVID 19 emergency months. Furthermore, we want to acknowledge all the member of the COVID 19 Niguarda Working Group. We express our sincere thanks to all the participants of the COVID Symptom Study app. We thank the staff of Zoe Global Limited, the Department of Twin Research, and the Clinical and Translational Epidemiology Unit for their tireless work in contributing to the running of the study and data collection. This manuscript has been released as a pre-print at MedRxiv, Funding. This work was supported in part by the European Structural and Investment Funds grant for the National Centre of Competence in Molecular Diagnostics (#KK., a National Centre of Research Excellence in Personalized Healthcare grant (#KK., and an IP CORONA-2020-04 grant from the Croatian Science Foundation. The Symptom Study app: Zoe provided in kind support for all aspects of building, running, and supporting the app and service to all users worldwide. The Department of Twin Research receives support from grants from the Wellcome Trust (212904/Z/18/Z) and the Medical Research Council (MRC)/British Heart Foundation Ancestry and Biological Informative Markers for Stratification of Hypertension (AIMHY; MR/M016560/1), European Union, Chronic Disease Research Foundation (CDRF), Zoe Global Ltd, NIH, and the National Institute for Health Research (NIHR)-funded BioResource, Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust in partnership with King's College London. CMe was funded by the Chronic Disease Research Foundation and by the MRC Aim-Hy project grant. CB was funded by grants FIS-FEDER-ISCIII PI16/00620 and PERIS STL008. Publisher Copyright: © Copyright © 2021 Kifer, Bugada, Villar-Garcia, Gudelj, Menni, Sudre, Vučković, Ugrina, Lorini, Posso, Bettinelli, Ughi, Maloberti, Epis, Giannattasio, Rossetti, Kalogjera, Peršec, Ollivere, Ollivere, Yan, Cai, Aithal, Steves, Kantele, Kajova, Vapalahti, Sajantila, Wojtowicz, Wierzba, Krol, Zaczynski, Zycinska, Postula, Lukšić, Čivljak, Markotić, Brachmann, Markl, Mahnkopf, Murray, Ourselin, Valdes, Horcajada, Castells, Pascual, Allegri, Primorac, Spector, Barrios and Lauc. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

King's Authors


Background: Most respiratory viruses show pronounced seasonality, but for SARS-CoV-2, this still needs to be documented. Methods: We examined the disease progression of COVID-19 in 6,914 patients admitted to hospitals in Europe and China. In addition, we evaluated progress of disease symptoms in 37,187 individuals reporting symptoms into the COVID Symptom Study application. Findings: Meta-analysis of the mortality risk in seven European hospitals estimated odds ratios per 1-day increase in the admission date to be 0.981 (0.973–0.988, p < 0.001) and per increase in ambient temperature of 1°C to be 0.854 (0.773–0.944, p = 0.007). Statistically significant decreases of comparable magnitude in median hospital stay, probability of transfer to the intensive care unit, and need for mechanical ventilation were also observed in most, but not all hospitals. The analysis of individually reported symptoms of 37,187 individuals in the UK also showed the decrease in symptom duration and disease severity with time. Interpretation: Severity of COVID-19 in Europe decreased significantly between March and May and the seasonality of COVID-19 is the most likely explanation.

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