Epidemic  An outbreak of disease that spreads quickly and affects many individuals at the same time” (source: Merriam-Webster)

 Pandemic  A type of epidemic (one with greater range and coverage), an outbreak of a disease that occurs over a wide geographic area and affects an exceptionally high proportion of the population” (source: Merriam-Webster)

 Coronaviruses  Coronaviruses belong to family coronaviridae and oder Nidovirales, are positive-sense, single stranded RNA virus. They were first identified in the mid-1960s and  have been divided into 4 types alpha, beta, gamma and delta . The alpha, beta and delta are pathogenic to mammals while gamma is infectious to birds. Coronavirus is transmitted through direct contacts with secretions or through aerosol. So far there are seven types of human coronavirus (HCoV) that cause human respiratory diseases: HCoV-229E, HCoV-NL63, HCoV-OC43, HCoV-HKU1, SARS-CoV, MERS-CoV and the novel coronavirus, SARS-CoV-2.

 SARS-CoV-2  Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a novel coronavirus that causes the Coronavirus disease 19. This was initially called as 2019 novel coronavirus (2019-nCoV).

 Covid-19  Coronavirus disease 19 (Covid-19) is the new disease outbreak caused by the SARS-CoV-2 starting from December 2019.