Coronaviruses (CoVs) are a group of single-stranded positive-sense RNA genome viruses that normally cause mild to moderate upper respiratory tract infections in humans and many animal species. Even though hundreds of coronaviruses circulate among animals, these viruses can move to people in certain situations, known as spillover events, resulting in severe infection. Human Coronavirus 229E, OC43, NL63, and HKU1 are four of the total seven known coronaviruses till date that cause illness, with mild to severe clinical presentation and self-limiting respiratory symptoms. However, three novel fatal coronaviruses have evolved from animal reservoirs within the last two decades, such as Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), Middle East Respiratory Syndrome Coronavirus (MERS-CoV), and the most recent Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2) are extremely pathogenic and can cause severe respiratory diseases and death in SARS-CoV2 infected individuals, presenting coronaviruses as a new public health concern in the twenty-first century. The ongoing new coronavirus SARS-CoV2 causes coronavirus illness 2019 (COVID-19), which has become a global epidemic. SARS-CoV2 was found in Wuhan, China, and was responsible for an outbreak of atypical viral pneumonia, producing an unprecedented crisis in social life, health care, and economic growth. The current review contributes to a better knowledge of coronavirus pathogenesis of SARS-CoV, MERS-CoV, and SARS-CoV2. SARS-CoV2 is currently evolving as genetic code changes occur during genome replication, resulting in SARS-CoV2 variants. Finally, with a focus on SARS-CoV2 variants of concern, B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.617.2 (Delta), and B.1.1.529 (Omicron).
(Am J Transl Med 2022. 6(2):41-62).