Medical scientists first became aware of COVID-19 late last year. It’s caused by a coronavirus called SARS-CoV-2, one of seven coronaviruses known to infect humans. (Coronaviruses get their name from the “crowns” (corona in Latin) that, when viewed with a microscope, project from the virus’s surface.)

Although COVID-19 is similar to two other serious diseases caused by coronaviruses, much remains to be unraveled.

What is known:

• It’s easily spread from person to person, and close contact makes it easier to catch.

• It’s a respiratory disease that affects the lungs and other parts of the body.

• Many people never know they have had it, and others die from it.

• Older people with existing health conditions are most vulnerable, but children also get it and sometimes will die.

• Some with mild cases will bounce back, though probably not as quickly as from regular flu. Many will have lingering symptoms.

• Lingering symptoms and severity of disease don’t seem to be linked, based on evidence so far.

About 19 million cases of COVID-19 have been reported worldwide so far, and more than 700,000 have died, World Health Organization statistics show.

In the United States, more than 4.8 million people have had it, and more than 157,000 have died.

Tennessee has recorded more than 122,000 cases and more than 1,200 deaths.

Important take-aways from Vanderbilt physician Helen Keipp Talbot:

1. Continue to take care of yourself, eating a eat healthy diet and exercising.

2. Take care of any existing medical problems (high blood pressure and diabetes, for examples).

3. Wear a mask

4. Wear a mask

5. Wear a mask