The basics on the coronavirus: What you need to know as the US becomes the new epicenter of COVID-19

Three months after the first coronavirus case was confirmed in the United States, the nation has become the new epicenter of the worldwide pandemic.

More than 16,000 people have died in the U.S. after contracting COVID-19, tens of thousands have been infected, and it's still hard to get tested for the virus. As thousands of people continue to recover in China, where the outbreak began, health care systems in Europe and the U.S. are confronting a woeful lack of time and resources.

The situation continues to develop rapidly, and information about COVID-19 is still evolving. Here's what we know about COVID-19.

What is the coronavirus?

The novel coronavirus, officially called SARS-CoV-2, is part of a large family of viruses named for the crown-like spikes on their surface. The virus causes an illness called "coronavirus disease 2019," or COVID-19.

Coronaviruses are common in many different species of animals, including camels, cattle, cats and bats, according to the U.S. Centers for Disease Control and Prevention. In rare instances, animal coronaviruses can infect people and then spread between people. At least two other coronaviruses have infected humans in the past: Middle East Respiratory Syndrome, or MERS, and severe acute respiratory syndrome, or SARS.

How did the coronavirus start?

As with SARS and MERS, the new coronavirus has its origin in bats, and scientists suspect the virus was initially transmitted to another animal – an "intermediary host" – before it spread to humans. In the case of SARS, that host was a civet cat. For MERS, it was a camel.

Early reports of the new coronavirus emerged in December 2019 and have been linked to a market in Wuhan, China. Scientists suspect that an animal spread the virus to a person at that market, and that that person spread the virus to other people. The intermediate host may have been a domestic animal, a wild animal or a domesticated wild animal, according to the World Health Organization.

What are symptoms of the coronavirus?

Symptoms can range from mild to severe, and some people don't have any symptoms at all. The most common symptoms resemble the flu and include fever, dry cough and shortness of breath, according to the CDC. The WHO adds tiredness to that list. Some people also develop aches and pains, nasal congestion, runny nose, sore throat or diarrhea, the WHO says.

About 1 in 6 people becomes seriously ill and develops difficulty breathing, according to the WHO. Symptoms may appear anywhere between two to 14 days after exposure, with the average patient seeing onset at around five days, according to the CDC.

But details of the most common symptoms are still evolving. One New York neurosurgeon who tested positive for the virus didn't initially have any of the most common symptoms. Newer reports are also suggesting that a loss of a sense of smell or taste may be a symptom of COVID-19.

COVID-19 symptoms can be all or nothing: 'The whole kit and caboodle'

How many coronavirus cases are in the US?

There are almost 470,000 confirmed cases in the U.S., according to data compiled by Johns Hopkins University.

These cases include people who traveled abroad and brought the virus back to the U.S., people who had close contact with someone who was infected and people who acquired the virus in their community but don't know the source of the infection.

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Map of coronavirus cases in US

Cases have been reported in all 50 states and the District of Columbia.

How many people have died from the coronavirus in the US?

More than 16,000 people have died after contracting the virus, according to Johns Hopkins. Most of those deaths have been in New York, followed by New Jersey.

Most US virus deaths are in New York

New York state has become the epicenter of the outbreak in the U.S. There are more than 161,000 confirmed cases in the state, with more than 87,000 in New York City, according to the New York Department of Health. More than 7,000 people in the state have died after contracting the virus.

The state has temporarily banned all nonessential gatherings of individuals of any size for any reason and closed schools until at least April 15. State officials have set up a 1,000-bed temporary hospital at the Javits Convention Center in Manhattan.

How many cases of the coronavirus are there worldwide?

Here's a breakdown of worldwide numbers, as of Friday:

  • More than 1.6 million confirmed cases

  • More than 96,000 people have died

  • More than 361,000 people have recovered

US coronavirus map: Track the coronavirus outbreak across the US and in your state with daily updated maps and total cases here.

China ends lockdown, sees recoveries

In China, which launched an aggressive campaign of quarantine measures and travel restrictions to prevent the spread of the virus, officials are reporting fewer and fewer new cases of the coronavirus each day, and China's National Health Commission says that all the new cases are being imported from abroad.

Of the more than 82,000 reported coronavirus cases in the country, more than 77,000 patients have recovered, according to Johns Hopkins.

After a two-month lockdown on more than 60 million people in Hubei Province, where the coronavirus pandemic originated, Chinese officials have lifted travel restrictions on people leaving the region. People are only able to leave the area if they are coronavirus-free and have been given a clean bill of health. Wuhan, Hubei's provincial capital, will remain locked down until April 8.

Italy has most coronavirus deaths worldwide

Italy has been devastated by the pandemic, which has killed more than 16,500 people in the country.

The nation is under quarantine, but case numbers continue to rise. Doctors there have described in interviews and on social media heart-wrenching decisions on who gets ventilators and who does not. Researchers have suggested that the nation's older population, lack of testing capacity and delay in implementing lockdown measures may have contributed to the dire circumstances.

CDC coronavirus tips for how to protect yourself

Health officials recommend social distancing to "flatten the curve," or slow the spread of the virus. That involves avoiding interactions with people outside of those who live in your household. When someone needs to leave their home, they are advised to stay at least 6 feet away from other people.

On March 16, the White House has called on all Americans to avoid social gatherings involving groups of more than 10 for 15 days. But some state and local governments have issued stricter guidelines.

Are you social distancing correctly? An AR guide to flattening the curve

The CDC also recommends taking commonsense health precautions:

  • Thoroughly wash your hands

  • Use a hand sanitizer that contains at least 60% alcohol

  • Avoid touching your eyes, nose and mouth

  • Clean and disinfect frequently touched surfaces daily

  • Covering your mouth and nose with your bent elbow or tissue when you cough or sneeze

  • Stay home if you're sick

Who is most at risk of becoming very sick or dying?

Older adults and people of any age who have serious underlying medical conditions might be at higher risk for severe illness from COVID-19, according to the CDC. That includes people aged 65 years and older and those who live in a nursing home or long-term care facility.

According to the CDC, other high-risk conditions include:

  • People with chronic lung disease or moderate to severe asthma

  • People who have heart disease with complications

  • People who are immunocompromised including cancer treatment

  • People of any age with severe obesity

  • People with with diabetes, renal failure or liver disease

Among more than 4,000 confirmed cases in the U.S. as of March 16, 80% of deaths associated with COVID-19 were among adults aged 65 and older, with the highest percentage of severe outcomes among people 85 and older, according to the CDC.

At the same time, Americans of all ages have faced serious health complications. Data published by the CDC found that among the roughly 12% of COVID-19 cases in the U.S. known to need hospitalizations, about 1 in 5 were among people ages 20 to 44.

What is the treatment for the coronavirus?

Despite widespread rumors, social media reports and optimism surrounding the effectiveness of several existing drugs, so far there are no proven treatments for COVID-19, according to the CDC and WHO.

Treatment consists of supportive care to help relieve symptoms and, for severe cases, care to support vital organ functions. About 80% of people recover from the disease without needing special treatment, according to the WHO. For most patients, that means drinking plenty of fluids and resting, just as you would for the cold or flu.

Is there a vaccine?

No, and it will be at least a year to 18 months before any vaccine is ready for large-scale use, according to most estimates.

Thousands of scientists worldwide are on the case. As of last week, the WHO had posted a list of 41 possible vaccine candidates on its site. The first vaccine trial got underway this week in Seattle, when four volunteers received a version of a vaccine to prevent the disease.

How long does the coronavirus last?

Information about how long symptoms last is still evolving. But a February WHO study may give us some preliminary clues:

  • The median time from symptom onset to recovery is about two weeks for mild cases

  • For patients with severe or critical disease, the median recovery time is three to six weeks

  • Among patients who have died, the time from symptom onset to death ranges from two to eight weeks

Does the coronavirus affect pregnancy?

While pregnant women have had a higher risk of developing severe illness with the flu and viruses from the same family as COVID-19, it is not yet clear if pregnant women are more likely to get sick from the new virus or what if any risk infants face if their mom has COVID-19.

To stop the potential spread of the virus from an infected mother to a child, the CDC and the American College of Obstetricians and Gynecology recommend that facilities should consider temporarily separating the mother who has confirmed COVID-19 or is a PUI (person under investigation) from her baby. Separation guidance varies from 72 hours to seven days and in some cases up to 14 days depending on time since symptoms and recovery.

The CDC recommendation notes the health risks and benefits of separation should be discussed with the mother and she should be involved in decision-making. Hospitals including Massachusetts General Hospital and Johns Hopkins are following the guidelines.

The coronavirus is not known to be transmitted in breast milk or from the mother to a fetus in the womb. No infants born to mothers with COVID-19 have tested positive for the virus, according to the CDC.

Read more: Moms could be separated from newborns under virus guidelines

Can kids get the coronavirus?

Children are not at higher risk for COVID-19 than adults, according to the CDC. Among the more than 4,000 cases in the U.S. as of March 16, only 5% were people aged 0–19 years, according to the CDC. Just 2%–3% of cases in that age group had to be hospitalized, and none were in the ICU.

Last week, however, health officials reported that an infant coronavirus patient younger than one year old in Chicago and a 17-year-old teen in New Orleans died after contracting the virus. And 2-month-old in Nashville who tested positive for the virus could be the youngest patient in the nation, officials say. In China, at least one two-day-old infant had been infected, according to a WHO study.

Can you get coronavirus twice?

It's unclear, according to the CDC.

For many viruses, including the MERS virus, patients are unlikely to be re-infected shortly after they recover because a protective antibody is generated in those who are infected. But scientists still need to do more research to determine if this is also the case with COVID-19 and how long those antibodies may last.

What does it mean to quarantine versus isolate?

Isolation and quarantine are effective ways to help prevent the spread of disease, according to the CDC. Isolation separates sick people with a contagious disease from people who are not sick. Quarantine separates and restricts the movement of people who were exposed to a contagious disease to see if they become sick.

How is the coronavirus spread?

Scientists think the virus spreads mainly from person to person through respiratory droplets produced when an infected person coughs or sneezes. People are thought to be the most contagious when they are the sickest, but some spread might be possible before people show symptoms, according to the CDC.

A person can get the virus by touching a surface that has the virus on it and then touching their own mouth, nose or eyes, according to the CDC.

Is coronavirus airborne? How long does the coronavirus stay on surfaces?

Research on how long the virus can survive on surfaces is ongoing, and estimates are preliminary. A study published in the New England Journal of Medicine this month found that viable virus could be detected up to three hours later in the air, up to four hours on copper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel.

However, a subsequent report from the CDC found that genetic material from the virus can live on surfaces for more than two weeks. The CDC found traces of the virus' RNA, not the coronavirus itself, on surfaces in the cabins of both symptomatic and asymptomatic infected passengers on the Diamond Princess cruise ship – 17 days after passengers had left the cabins.

How do I get a coronavirus test?

If you have symptoms and want to get tested, the CDC recommends calling your state or local health department or a medical provider.

At this time, the CDC recommends that clinicians prioritize testing hospitalized patients and symptomatic healthcare workers. Second-level priority includes patients in long-term care facilities with symptoms, patients 65 years of age and older with symptoms, patients with underlying conditions with symptoms and first responders with symptoms.

Not sure if you should get tested? The CDC website features a "self-checker" to help you make decisions about seeking medical care. The feature is not intended for the diagnosis or treatment of COVID-19 and is intended only for people in the U.S.

Who can actually test for the coronavirus?

Public health labs, as well as approved private labs, universities and hospitals can conduct the tests. As of March 30, 94 public health laboratories in 50 states plus D.C., Guam and Puerto Rico had successfully verified COVID-19 diagnostic tests and were offering testing, according to the CDC.

While the CDC initially developed and mailed flawed testing kits, the agency said it fixed the glitch. Meanwhile, a project funded by billionaire Bill Gates is set to issue at-home testing kits for people who fear they have been infected with the coronavirus.

What is the Trump administration doing about the epidemic?

At the end of January, the Trump administration declared the coronavirus outbreak to be a public health emergency in the U.S. and quarantined Americans who had recently been to certain parts of China – the first quarantine order issued by the federal government in more than 50 years.

President Donald Trump put Vice President Mike Pence in charge of a task force that is coordinating the government's response to the outbreak.

Amid concerns about critical shortages of live-saving medical equipment, Trump in March invoked the Defense Production Act, a wartime authority that allows him to direct industry to produce critical equipment.Trump has ordered his administration to use its authority under the act to force General Motors to expedite government contracts to build ventilators.

When are stimulus checks coming?

In March, Trump signed the largest economic stimulus package in U.S. history. The $2 trillion stimulus plan includes one-time payments of $1,200 per adult and $500 per child, $367 billion for small businesses, $500 billion for loans to larger industries, $100 billion for hospitals and the health care system, and $600 more per week in unemployment benefits for those out of work.

Here's how you can calculate the amount of stimulus money your household can expect.

When will the coronavirus be over?

There are many projections that predict when the virus will no longer be a global crisis, but scientists say the forecasts all hinge on how people behave. That's why it's essential to social distance and do what you can to prevent spread.

Celebrities with coronavirus: Chris Cuomo, Prince Charles, Tom Hanks

Prince Charles, the Prince of Wales and heir to the British throne, 71, tested positive for the coronavirus after "displaying mild symptoms." He was self-isolating at a royal estate in Scotland, and his wife Camilla, 72, has tested negative for the virus. It was not immediately clear whether Charles' mother, Queen Elizabeth II, or her husband, Prince Philip, have been tested.

CNN news anchor Chris Cuomo, the 49-year-old brother of New York Gov. Andrew Cuomo, announced in a tweet Tuesday he tested positive for COVID-19 after being exposed to people who are infected.

Couple Tom Hanks and Rita Wilson, both 63, were discharged from an Australian hospital on March 16, five days after they were admitted and tested positive for coronavirus.

Coronavirus: What Tom Hanks, Angelina Jolie and more stars are saying about COVID-19

Many more celebrities have said that they have tested positive for the virus, including: Late night host Andy Cohen, Bon Jovi keyboardist David Bryan, Rock and Roll Hall of Famer Jackson Browne, Houston rappers Slim Thug and Scarface, opera singer Placido Domingo, singer Charlotte Lawrence, Christian music singer Sandi Patty, "Bachelor" star Colton Underwood, "Frozen 2" actress Rachel Matthews, "Lost" and "Hawaii Five-0" star Daniel Dae Kim, actress Debi Mazar, actress Laura Bell Bundy, Actor Idris Elba and his wifie, Sabrina Dhowre, and Kristofer Hivju, the "Game of Thrones" actor best known for embodying the renowned warrior Tormund Giantsbane

Follow Grace Hauck on Twitter @grace_hauck.

Contributing: Erin Richards, David Jackson, John Fritze, Michael Collins, John Bacon, Jorge Ortiz, Paul Davidson, Adrianna Rodriguez, Jayne O'Donnell, Ken Alltucker, Jessica Menton, Ryan Miller, Morgan Hines, David Oliver, Dawn Gilbertson, Curtis Tate, Jayme Deerwester.

This article originally appeared on USA TODAY: Coronavirus, explained: What to know about US cases, deaths, stimulus