COVID-19 is one of many Coronaviruses some of which have been around for a long time.
Most of us would have had many infections with previous seasonal Coronaviruses in the past. These infections are generally very mild. However, there have been also other Coronaviruses in the past causing very severe illnesses such as the SARS-CoV causing Severe Acute Respiratory Syndrome [SARS] and MERS-CoV causing Middle East Respiratory Syndrome [MERS].
COVID-19 [SARS-CoV 2] is causing an illness which is currently called “Coronavirus Disease” as this is an entirely new virus which we have never seen before. This is why the virus was initially also called “Novel Virus or 2019 novel coronavirus”.