Atmospheric circulation and the spread of COVID-19 in Europe

 COVID-19: Atmospheric circulation and the spread of COVID-19 in Europe. Jefferson T, Heneghan C.

https://www.cebm.net/study/atmospheric-circulation-and-the-spread-of-covid-19-in-europe/

Published on June 19, 2020

Reference Sanchez-Lorenzo A, Vaquero-Martinez J, Calbo J, Wild M, Santurtun A, Lopez-Bustins J-A, et al Anomalous atmospheric circulation favored the spread of COVID-19 in Europe. medRxiv. 2020:2020.04.25.20079590. 2020
Study type
Country Italy, Spain
Setting Public
Funding Details Public
Transmission mode Meteorological, Droplets
Exposures Atmospheric

Bottom Line

Strong atmospheric stability with dry conditions favoured viral spread by short-range droplet transmission.

Evidence Summary

Analysing records for Spain the authors report that lower mean temperatures of around 8  to 11ºC and lower specific humidity of <6 g/Kg were related to a higher number of cases and deaths.

Similar conditions were present in Northern Italy. However, both variables (temperature and humidity) are correlated. They also remark that pollution levels which are highest in the Po alley and around Madrid may have contributed to transmission.  Weather conditions may have favoured short and long range spread with droplet concentration not affected by low wind and even favoured indoor transmission via temperature inversion phenomena.

What did they do?

The authors correlated data on the incidence of COVID 19 for the 15 European capitals, focussing on Spain, Italy and Switzerland as the three countries which at the time of writing had more than 1000 COVID 19 related deaths with air pressure and the meteorological conditions. They postulated that the anomalous prolonged period of high pressure in Northern Italy and inland Spain activated COVID 19 which was already present. 

Study reliability

The case data was ascertained form worldometer, which relates to the date of reporting and not necessarily the date of occurrence of the infection.

Clearly defined setting Demographic characteristics described Follow-up length was sufficient Transmission outcomes assessed Main biases are taken into consideration
Yes No No Yes Yes

What else should I consider?

The authors point out that the spatial pattern of COVID-19 described has some resemblances with the 1918 influenza pandemic.

The authors hypothesize the meteorological conditions experienced in Italy and Spain promoted the airborne contagion both indoors and outdoors. 

Source: https://www.medrxiv.org/content/10.1101/2020.04.25.20079590v1

About the authors

Carl Heneghan

Carl Heneghan

Carl is Professor of EBM & Director of CEBM at the University of Oxford. He is also a GP and tweets @carlheneghan. He has an active interest in discovering the truth behind health research findings

Tom Jefferson

Tom Jefferson

Tom Jefferson is a senior associate tutor and honorary research fellow, Centre for Evidence-Based Medicine, University of Oxford.