> The only reason that other coronaviruses like OC43 don't kill a lot of people is that almost everyone catches it first as a youth, and builds up a level of im

> The only reason that other coronaviruses like OC43 don't kill a lot of people is that almost everyone catches it first as a youth, and builds up a level of immunity. But it can be quite deadly to someone who first catches it later in life, or to immunocompromised patients. As an aside, OC43 is strongly suspected to be the cause of the 1889-1890 pandemic which killed around 1 million.