COVID-19 is a respiratory illness caused by the novel coronavirus SARS-CoV-2. Coronaviruses are a family of viruses (like influenza viruses are a family of viruses) and circulate in our communities every year. They usually cause mild, flu-like illness. Notable exceptions to this were SARS (Severe Acute Respiratory Syndrome) and MERS (Middle Eastern Respiratory Syndrome). This coronavirus is new to humans and so public health scientists are still learning a lot about it. Like other coronaviruses, this one seems to be a zoonotic infection and crossed into humans from an animal—likely bats.

COVID-19, like its coronavirus brethren, causes fever, cough, and breathing difficulty. Public health scientists estimate 80% of people who come down with COVID-19 would experience mild symptoms and not need hospitalisation. Several cases in Washington State alone have managed their own illness without hospitalisation. While most people will have very mild illness, some people may get quite ill. Public health scientists expect that most of the severe illnesses will be in patients who are older. They also expect that most deaths will occur among older individuals.