Spectral analysis of the daily evolution of deaths due to Covid-19 in France and in the world shows a weekend effect: myth or reality?

Abstract

Background The weekend effect has been extensively observed for different diseases and countries and recognized as a fact but without obvious causes. Objectives In this paper we first aimed at investigating the existence of a periodicity in the death count due to Covid-19, and second, at opening the discussion concerning the reality of this effect in this particular context. Methods Daily statistics of deaths due to the Covid-19 pandemic were subjected to a discrete Fourier transform spectral analysis for France and the world, over the periods from March 29 to May 16, 2020 and from January 22 to May 18, 2020 respectively. Results In both cases, a frequency peak of one harmonic corresponding to a period of 7.11 days was observed for France and the world. In France, this weekly frequency corresponds to a decrease in deaths every Sunday, whereas for the world the systematic decrease is shifted on average by 1.5 days and corresponds to Saturday or Friday. Conclusion At the world scale and for the epidemic period we confirm the existence of a consecutive weekend effect in the context of the Covid-19 pandemic.

Real-Time Estimation of Rt for Supporting Public-Health Policies Against COVID-19

“…Since most common uncertainties are related to the time frame between contagion, sampling, detection and report (temporal misclassification), recovery criteria (PCR or fix quarantine time after which the patient is considered healed), we suggest to perform a datapretreatment stage, where delayed curves could be corrected to the day of contagion before applying moving averages to smooth trends and estimate their variability while R t . The use of an oneweek averaging window is suggested for minimizing the impact of the "weekend-effect" (20). Another limitation of the proposed methodology relates to the low-case limit, where the different quantities involved in Equation 8are (or are close to) zero.…”