COVID-19: the first pandemic of the 21th century. A review of the literature

Abstract The new coronavirus SARS-CoV-2 (COVID-19) was recognized in December 2019 as a cause of severe pneumonia and has now led to a global pandemic [1, 2]. Respiratory illnesses caused by COVID-19 cover a whole range of severities. Identifying the risk factors and protective factors for the severity of COVID-19 disease is essential to direct the development of new treatments and infection prevention strategies. The first large series of cases identified several risk factors for severe forms of the disease, including advanced age, hypertension, diabetes, cardiovascular disease, exposure to tobacco, and obstructive pulmonary chronic disease [1, 3]. The Chinese Center for Disease Control and Prevention published a significant case series study of coronavirus disease 2019 (COVID-19) (72 314 cases, updated through February 11, 2020) [4, 5]. The authors of this paper summarized key findings from this report and discussed emerging understanding of and conclusions from the COVID-19 epidemic.