Will the COVID-19 pandemic slow down in the Northern hemisphere by the onset of summer? An epidemiological hypothesis

Abstract

The COVID-19 pandemic has affected most countries of the world. As corona viruses are highly prevalent in the cold season, the question remains whether or not the pandemic will improve with increasing temperatures in the Northern hemisphere. We use data from a primary care registry of almost 15,000 patients over 20 years to retrieve information on viral respiratory infection outbreaks. Our analysis suggests that the severity of the pandemic will be softened by the seasonal change to summer.

Keywords: COVID-19; Epidemiology; Influenza; Pandemic; Respiratory viral infection; Seasonality.

Fig. 1

The total number of infectious respiratory diseases (green line) over a time period of 20 years (1999–2020). The dashed line indicates the overall monthly mean of diagnoses over this time period (84.5 ± 41.6), and the shaded area shows the upper and lower bounds of one standard deviation around this mean

Fig. 2

The relative number of infectious respiratory diseases over a time period of 20 years (1999–2020). For each month, the total number of respiratory diseases is related to the total number of diagnoses in the physician practice (y-axis). The figure plots the seasons in which previous respiratory infections have been recorded (02/03 SARS-CoV, purple line; 04/05 H5N1, green line; 09/10 pandemic flu H1N1v, blue line), and those where this was not the case (grey lines). Regarding the pattern of respiratory diagnoses in the season 2019/20, we first used the monthly data until March 15 (red line). A red line is marked here and is a solid line from Aug to Mar. We further fitted a “potential” seasonal development of respiratory diseases for three scenarios (dashed red lines): (i) one where the share of respiratory diseases in July 2020 is equal to the average of respiratory diseases (indicated by “AVG”) over the month of July of the whole sample period of 20 years; (ii) one where this average is 1.5 times higher; (iii) one where this average is two times higher