摘要
The coronavirus disease 2019(COVID-19)pandemic,caused by the transmission of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),shows a complex epidemiological course characterized by several successive waves of infectionwith a certain strength,duration,and rhythm.Recently,Mitchell and Zhang reported in a publication in this journal1 their intriguing finding of a“four-month intrinsic viral cycle in COVID-19”by analyzing the dynamics of COVID-19 cases for 14 countries separately and for a global dataset including 189 countries.The time span analyzed was about 1.8 years(January 22,2020,to October 8,2021).
