COVID-19 is highly transmissible; however, its severity varies from one individual to another. Variability among different isolates of the virus and among its receptor (ACE2) may contribute to this severity, but comorbidity plays a major role on disease prognosis. Many comorbidities have been reported to be associated with severe COVID-19 patients. We have collected data from retrospective studies which include clinical and epidemiological features of patients and categorize them into severe/mild, ICU/non-ICU and survivors/dead patients. In this review, we give an update about SARS-CoV-2 structure with emphasis on the possible reasons for the severity of the virus in patients. We also collected information and patients’ data to highlight the relation between COVID-19 patients and comorbidities.

中文翻译：

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COVID-19：与传染性和严重性相关的危险因素

COVID-19具有很高的传播能力；但是，其严重性因人而异。病毒的不同分离株之间及其受体（ACE2）之间的变异性可能会导致这种严重性，但合并症在疾病预后中起主要作用。据报道，许多合并症与重度COVID-19患者有关。我们从回顾性研究中收集了数据，其中包括患者的临床和流行病学特征，并将其分类为重度/轻度，ICU /非ICU和幸存者/死亡患者。在这篇综述中，我们提供了有关SARS-CoV-2结构的更新，重点是患者中病毒严重性的可能原因。我们还收集了信息和患者数据，以突出显示COVID-19患者与合并症之间的关系。