Layman’s answer: it’s as dangerous or more dangerous than influenza, which is pretty dangerous to older people and people with weak immune systems or other special circumstances. It’s also dangerous in the contagiousness aspect because it spreads before a person shows symptoms, and that’s why we have to stay away from other people even if we feel fine( we might not be fine tomorrow).

To your last question, yes: there should be more strict self-isolation by anyone who has flu or even colds anyway. This is one of the big talking points about having a national health care program and sick leave paid for by taxes: so that people who are sick stop going to work in order to pay their bills, spreading around germs and increasing the risks (and costs) to everyone.