Versión en español. Leia este artigo em português.

Editor’s note: Information on the COVID-19 crisis is constantly changing. For the latest numbers and updates, keep checking the CDC’s website. For the most up-to-date information from Michigan Medicine, visit the hospital's Coronavirus (COVID-19) webpage.

Interested in a COVID-19 clinical trial? Health research is critical to ending the COVID-19 pandemic. Our researchers are hard at work to find vaccines and other ways to potentially prevent and treat the disease and need your help. Sign up to be considered for a clinical trial at Michigan Medicine.

Cruises and flights canceled. Colleges and universities sending students home to watch lectures online. Public schools closing. Offices asking people to telecommute. Concerts, parades, festivals and sporting events postponed.

Is all of this really necessary for the coronavirus? Are public health officials overreacting to the threat posed by the virus that causes the disease COVID-19?

It’s absolutely necessary, because it’s worked in the past, says medical historian Howard Markel, M.D., Ph.D., a University of Michigan expert who has studied the effects of similar responses to past epidemics.

“An outbreak anywhere can go everywhere,” he says. And right now, “We all need to pitch in to try to prevent cases both within ourselves and in our communities.”

It’s called “flattening the curve,” a term that public health officials use all the time but that many Americans just heard for the first time this week.

SEE ALSO: Think This Flu Season Is Bad? Flash Back 100 Years

What curve? And why is flatter better?

If you look at the image above, you can see two curves – two different versions of what might happen in the United States, depending on next steps.

The tall, skinny curve is bad – it means that a lot of people will get sick at once, in a short period of time because we don’t take enough steps to prevent the virus from spreading from person to person.

Most people won’t get sick enough to need a hospital. But those who do could overwhelm the number of beds and care teams that our nation’s hospitals have available.

MORE FROM MICHIGAN: Sign up for our weekly newsletter

After all, Markel points out, many emergency rooms and hospitals already operate close to capacity on a good day, without coronavirus. Adding a sharp spike in very ill COVID-19 patients to that traffic could mean some people don’t get the care they need – whether they have coronavirus or not.