The Coronavirus Disease 2019 (COVID-19), a pneumonic disease caused by the SARS Coronavirus 2 (SARS-CoV-2), is the 7th Coronavirus to have successfully infected and caused an outbreak in humans. Genome comparisons have shown that previous isolates, the SARS-related coronavirus (SARSr-CoV), including the SARS-CoV are closely related, yet different in disease manifestation. Several explanations were suggested for the undetermined origin of SARS-CoV-2, in particular, bats, avian and Malayan pangolins as reservoir hosts, owing to the high genetic similarity. The general morphology and structure of all these viral isolates overlap with analogous disease symptoms such as fever, dry cough, fatigue, dyspnoea and headache, very similar to the current SARS-CoV-2. Chest CT scans for SARS-CoV-2, SARS-CoV and MERS-CoV reveal pulmonary lesions, bilateral ground-glass opacities, and segmental consolidation in the lungs, a common pathological trait. With greatly overlapping similarities among the previous coronavirus, the SARS-CoV, it becomes interesting to observe marked differences in disease severity of the SARS-CoV-2 thereby imparting it the ability to rapidly transmit, exhibit greater stability, bypass innate host defences, and increasingly adapt to their new host thereby resulting in the current pandemic. The most recent B.1.1.7, B.1.351 and P.1 variants of SARS-CoV-2, highlight the fact that changes in amino acids in the Spike protein can contribute to enhanced infection and transmission efficiency. This review covers a comparative analysis of previous coronavirus outbreaks and highlights the differences and similarities among different coronaviruses, including the most recent isolates that have evolved to become easily transmissible with higher replication efficiency in humans.

2019 年冠状病毒病 (COVID-19) 是一种由 SARS 冠状病毒 2 (SARS-CoV-2) 引起的肺炎，是第 7 种成功感染并在人类中爆发的冠状病毒。基因组比较表明，以前的分离株，SARS 相关冠状病毒（SARSr-CoV），包括 SARS-CoV 密切相关，但疾病表现不同。由于高度的遗传相似性，对 SARS-CoV-2 的不确定来源提出了几种解释，特别是蝙蝠、鸟类和马来穿山甲作为储存宿主。所有这些病毒分离株的一般形态和结构与发烧、干咳、疲劳、呼吸困难和头痛等类似疾病症状重叠，与目前的 SARS-CoV-2 非常相似。SARS-CoV-2、SARS-CoV 和 MERS-CoV 的胸部 CT 扫描显示肺部病变，双侧磨玻璃影和肺部节段性实变，这是一种常见的病理特征。由于之前的冠状病毒 SARS-CoV 之间有很大的重叠相似性，观察 SARS-CoV-2 疾病严重程度的显着差异变得很有趣，从而赋予它快速传播的能力，表现出更高的稳定性，绕过先天宿主防御，并越来越适应他们的新宿主，从而导致当前的大流行。SARS-CoV-2 的最新 B.1.1.7、B.1.351 和 P.1 变体强调了一个事实，即刺突蛋白中氨基酸的变化有助于增强感染和传播效率。这篇综述涵盖了对以往冠状病毒爆发的比较分析，并强调了不同冠状病毒之间的差异和相似之处，