Elsevier established a free COVID-19 resource center in January 2020, offering English and Mandarin information on the virus. The center grants permission for free access to its research in PubMed Central and other repositories. A narrative review compares the pathogenesis, epidemiology, and clinical features of COVID-19, SARS, and MERS. While COVID-19 shares some clinical features with SARS, it has a lower fatality rate (2.3%) compared to SARS (9.5%) and MERS (34.4%). The basic reproductive number (R0) of COVID-19 is estimated between 2.0-2.5, higher than SARS (1.7-1.9) but lower than MERS (<1). Transmission routes for SARS-CoV-2 are not fully understood, though a gastrointestinal route is possible. The review highlights that SARS-CoV-2 is more community-transmissible than SARS and MERS, which were mainly nosocomial. Phylogenetic analysis shows SARS-CoV-2 is more related to bat coronaviruses than SARS-CoV. Pathogenicity studies indicate SARS-CoV-2 uses ACE2 as a receptor, similar to SARS-CoV, but with some differences. The virus's ability to spread is attributed to its lower pathogenicity and different viral tropism. The review also discusses clinical features, including fever, cough, and respiratory symptoms, and notes that mild cases are common. The fatality rate of COVID-19 is lower than SARS but higher than some estimates. The review concludes that while much remains unknown about COVID-19, lessons from SARS and MERS can help in managing the new threat. The study emphasizes the importance of understanding transmission routes, viral evolution, and clinical features to better prepare for future outbreaks.Elsevier established a free COVID-19 resource center in January 2020, offering English and Mandarin information on the virus. The center grants permission for free access to its research in PubMed Central and other repositories. A narrative review compares the pathogenesis, epidemiology, and clinical features of COVID-19, SARS, and MERS. While COVID-19 shares some clinical features with SARS, it has a lower fatality rate (2.3%) compared to SARS (9.5%) and MERS (34.4%). The basic reproductive number (R0) of COVID-19 is estimated between 2.0-2.5, higher than SARS (1.7-1.9) but lower than MERS (<1). Transmission routes for SARS-CoV-2 are not fully understood, though a gastrointestinal route is possible. The review highlights that SARS-CoV-2 is more community-transmissible than SARS and MERS, which were mainly nosocomial. Phylogenetic analysis shows SARS-CoV-2 is more related to bat coronaviruses than SARS-CoV. Pathogenicity studies indicate SARS-CoV-2 uses ACE2 as a receptor, similar to SARS-CoV, but with some differences. The virus's ability to spread is attributed to its lower pathogenicity and different viral tropism. The review also discusses clinical features, including fever, cough, and respiratory symptoms, and notes that mild cases are common. The fatality rate of COVID-19 is lower than SARS but higher than some estimates. The review concludes that while much remains unknown about COVID-19, lessons from SARS and MERS can help in managing the new threat. The study emphasizes the importance of understanding transmission routes, viral evolution, and clinical features to better prepare for future outbreaks.