Now that coronavirus cases in the U.S. have ticked up to four figures , the big question is how many people may ultimately become infected and how quickly it will happen.

With everyone wondering the same thing, theres a phrase you might have seen in a hashtag: Flatten the curve.

The curve, in this context, is simply the number of people who contract COVID-19, the disease caused by the new coronavirus, over time. Its easiest to understand if you see it drawn out:

(A number of people have shared similar versions of the curve chart this one comes from Dr. Siouxsie Wiles , an associate professor of microbiology at the University of Auckland.)

Flattening the curve just means staggering the number of COVID-19 cases over a longer period of time so everyone can have better access to care.

Theres a finite number of hospital beds across the country, and a finite number of ventilators and other equipment needed to care for the most severely affected patients. Doctors and nurses time and attention, too, are not unlimited resources. Thats all on top of the usual load of patients suffering from other things cancer, cardiac issues, the whole lot. The health care system is only built to help so many people at one time.

Thats why mitigating the spread of the virus is essential.

It might seem like a lot to ask, but the curve illustrates whats at stake if people do not adhere to the advice of public health authorities. A high curve indicates the virus is spreading quickly, which means some people arent going to get the care they need and the fatality rate is likely to increase. A low curve means its spreading slowly, allowing doctors the time to address more patients concerns and decreasing the overall number of people who need that attention.

For an idea of how bad things could get, look to Italy, said Joshua Sharfstein, vice dean for public health practice and community engagement at Johns Hopkins. The country made the dramatic step Wednesday of ordering all shops to close except grocery stores, pharmacies and banks in an attempt to curb an outbreak that has sickened more than 10,000 people, with about 630 deaths.

I dont think theres any reason to believe that that couldnt happen here, Sharfstein told HuffPost.

When the virus first reached U.S. shores in January, authorities responded by attempting to nip it in the bud. Infectious diseases can be slowed and, ideally, contained by isolating patients and figuring out who theyve recently had contact with a process called contact tracing. But as more and more people contract COVID-19 in different areas, a process called community spread, contact tracing becomes less and less possible.

Eventually, the responsibility to prevent transmission lands on everybody.

Public health officials are working to convey this message, encouraging people to practice good hygiene and social distancing. Essentially, that means staying home more in order to slow the spread of the virus because youre giving it fewer opportunities for transmission.

Event organizers have followed suit, canceling or postponing festivals and conventions left and right , while universities are beginning to switch to internet-only instruction. Companies and other employers are limiting travel. The mayor of New York City is telling people to work from home if they can swing it.

Although researchers are working on producing a COVID-19 vaccine, there isnt one yet, meaning a whole lot more people are susceptible to this new virus than they are to the flu, which is frequently compared with COVID-19 despite their differences . Preliminary evidence also suggests that COVID-19 might be commonly spread through the air even after a sick person is no longer nearby, according to Johns Hopkins making it even more important to follow health officials social distancing advice.

Nobody has immunity, so the number of people who could be sick is going to be much larger than a normal flu season, Sharfstein said. And in the flu season, people get vaccinated, people have leftover immunity from some other strains of flu. But nobody has immunity to this virus. So its not just that its deadlier than flu but that so many more people can get it.

The CDC offers a list of tips on how to keep yourself and those in your household healthy , and you can find even more information in the articles below.

#FlattenTheCurve.