One chart shows New York City's coronavirus cases, deaths, and hospitalizations by age bracket as the city's cases top 20,000

• New York City is the current epicenter of the coronavirus outbreak in the US.
• The city has reported more than 20,000 coronavirus cases and at least 280 deaths since its first case was confirmed on March 1.
• The daily number of new confirmed cases in New York City continues to rise, with more than 4,400 new cases reported on Thursday.
• Here's what we know about the ages, locations, and genders of the New Yorkers who have been infected, hospitalized, and died.
• Visit Business Insider's homepage for more stories.

New York City has reported nearly 30% of the US's coronavirus cases.

More than 20,000 people there have been infected (though that's only those who have been tested), and at least 280 people across New York's five boroughs have died - accounting for one-quarter of all US COVID-19 deaths. The city reported its first case on March 1.

New York City's Department of Health and Mental Hygiene releases daily summaries of COVID-19 cases, deaths, and hospitalizations across the city. The reports show how the city's outbreak is escalating and highlights the extent to which elderly New Yorkers are being hospitalized.

Here's the current breakdown:

New York City cases, hospitalizations, and deaths by age

New Yorkers older than 75 have the highest coronavirus-related hospitalization rate - about 38%. This age bracket's death rate, which is calculated by dividing the number of total cases by number of fatalities, is more than 6%.

City residents between 64 and 74 years old have the next-highest hospitalization rate: about 25%. That means one in every four people in that group confirmed to have the coronavirus have to go to a hospital. That age group's death rate, however, is one-third that of New Yorkers older than 75.

People between 45 and 64 years of age in New York seem to have have the highest number of COVID-19 cases per capita. The data also shows that New Yorkers younger than 17 face less risk - fewer than 450 cases have been reported in the age group, and only 6% of those cases involved hospitalization.

No New Yorker under the age of 17 has died, though five people younger than 45 have died.

The chart does not tell the full story of New York's coronavirus outbreak, however. That's because very few New Yorkers with mild cases of COVID-19 are getting tested. The city's Department of Health and Mental Hygiene website urges New Yorkers who think they have mild COVID-19 to stay home and not seek care.

"If you think you have COVID-19 and your illness is mild, you do not need to see your health care provider and you will not be tested," the site says. "Getting tested will not change what your provider will tell you to do to get better. They will tell you to stay home so you do not get others sick."

Presently, those who receive coronavirus tests in New York City tend to have the most severe COVID-19 complications.

"Unless you are hospitalized and a diagnosis will impact your care, you will not be tested," according to the city's health department.

That means many people's cases (and their demographic information) are not included in the data.

A further breakdown of NYC cases

As of Wednesday evening, 57% of New York City's coronavirus cases were male, according to data from city health officials.

About 32% of the city's cases, about 6,240 cases, were reported in Queens, making it the city's hardest-hit borough. Brooklyn reported 5,232 cases, or 26% of the city's total, followed by both Manhattan and the Bronx that each reported about 18%. Staten Island has reported 1,166 cases, or 6% of the city's total.

As of Tuesday, 95% of the New Yorkers who have died from COVID-19 had underlying conditions, including diabetes, lung disease, cancer, heart disease, high blood pressure, and asthma.

New York's new cases per day are increasing

In the 10 days between March 15 and 25, the number of cases in New York City jumped from 269 to 20,011: almost a 75-fold increase.

More than 2,400 new cases were reported on Wednesday morning, marking the fifth day in a row that the number of new daily cases was above 2,300. NYC's epidemic curve looks like a steep staircase, as does the US' epidemic curve.

This suggests the nation has thus far been unsuccessful in efforts to "flatten the curve," or slow the spread of the coronavirus so as not to overwhelm the healthcare system.

The best ways to do slow the virus' spread are to test widely, isolate people who are ill, trace who sick people had contact with to find others who might have been exposed, quarantine anyone who may have been exposed to the virus, close schools and nonessential business, and encourage people to practice social distancing.

New York Gov. Andrew Cuomo signed an executive order on March 20 mandating that all nonessential businesses in the state keep their workers at home. The order instructed people to stay home and practice social distancing. It went into effect at 8 p.m. ET on Sunday.

Ruobing Su contributed reporting to this story.

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