COVID-19 is a single-stranded, positive-sense RNA virus that caused a nationwide outbreak of serious respiratory problems across China. This RNA virus is capable of person-to-person transmission, spreading to more than 20 countries within 1 month. It is genetically highly related to SARS and MERS coronaviruses.
To date, seven coronavirus species including COVID-19 are known to infect human. Four viruses, including 229E, OC43, NL63 and HKU1, typically cause mild cold. However, people infected with the other three, including SARS, MERS and COVID-19, might develop acute and severe respiratory diseases with fever, cough and even death.