The pandemic has affected the economy, travel and politics and sparked fear as Americans feel the "significant disruption" as health officials had warned.
Here is what we know about the pandemic so far:
What is a coronavirus? Is it the same as COVID-19?
Coronaviruses are a large family of viruses, some of which cause the common cold; others found in bats, camels and other animals have evolved into more severe illnesses.
The coronavirus referenced in news headlines is a newly identified strand. The disease from this new coronavirus is officially named COVID-19, while the virus itself is called SARS-CoV-2.
The new virus was first detected in the Chinese city of Wuhan in December 2019 and has since spread globally. According to the Centers for Disease Control and Prevention, these first reported cases had links to a live animal market, suggesting the outbreak started from animal-to-person spread.
Coronaviruses are responsible for two other recent outbreaks: the 2003 SARS (severe acute respiratory syndrome) outbreak and the 2012 MERS (Middle East Respiratory Syndrome) outbreak.
What are coronavirus symptoms? How does it spread?
Patients with COVID-19 experience mild to severe respiratory illnesses. Symptoms include fever, cough and difficulty breathing and can appear two to 14 days after exposure, according to the CDC.
Emergency warning signs include:
Anyone experiencing these symptoms should seek medical attention immediately. Please note that the list is not all-inclusive.
The average time from exposure to developing symptoms is five to six days but can be up to two weeks.
About 15% of cases develop into severe disease, including pneumonia, Chinese scientists reported from 45,000 cases there. Scientists have estimated the fatality rate from less than 1% to as high as 4% among cases diagnosed so far, depending on location.
Flu kills about 0.1% of those it infects, so coronavirus seems about 10 times more lethal, the National Institutes of Health's Dr. Anthony Fauci told Congress.
The coronavirus mainly spreads from human to human. Like the common cold, the virus is transmitted through droplets when a person coughs or sneezes.
It's also possible that a person can get COVID-19 by touching a surface with the virus on it before touching their mouth, face or eyes.
The virus can live in the air for several hours, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel. Cleaning surfaces with solutions containing diluted bleach should kill it.
Each infected person spreads to two or three others on average, researchers estimate. It spreads more easily than flu but less than measles, tuberculosis or some other respiratory diseases.
The agency also said the virus has been observed spreading easily and sustainably in the community (a.k.a. "community spread") in some affected geographic areas.
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What can I do to prevent myself from getting sick? Do face masks actually work?
Here are protective measures everyone can take, according to the World Health Organization:
WATCH: A doctor explains how to properly wash your hands
Even though many images used for coronavirus-related news coverage show people wearing face masks, the CDC advises healthy people not to wear them.
Sick people, however, should wear masks in order to prevent the spread of germs.
As of Friday, April 3, the Centers for Disease Control and Prevention advised Americans to wear face coverings in public.
This recommendation was updated to respond to new research on transmission, or the spread of COVID-19. Recent studies suggest that asymptomatic individuals, or people who do not show COVID-19 symptoms but have the disease, can transmit the virus to others. This means people who feel fine can spread the coronavirus to others in close proximity by speaking, coughing and sneezing.
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How can I prepare for and cope with an outbreak in my community?
In the wake of wider coronavirus spread in the U.S., people should not panic, health experts stress.
A good way to think about planning, says former CDC Director Dr. Tom Frieden, is "if you had to be quarantined for 14 days at home," how would you cope?
Consider special needs such as allergies, medical conditions such as diabetes, babies who might need ready-to-feed formula and toddlers who might need shelf-stable milk. And don't forget about your pets. Click here to see a list of things worth buying in advance.
It seems unlikely that water service would be disrupted, but CDC's general guidance is to have at least three gallons for each person and pet.
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Also, families should have a plan in case a family member falls ill, such as designating a care room.
Parents should assess childcare options in case schools close, and employees should figure out a plan if going to work is not an option, according to Dr. Tomas Aragon, a San Francisco public health officer and epidemiologist.
Clean things that are touched a lot -- countertops, light switches, doorknobs, cabinet handles -- daily using ordinary detergent and water, the CDC advises.
If you're at home for an extended period of time with children, click here to see a list of ways to keep kids occupied, entertained and comfortable.
How many cases are confirmed globally? In the United States?
John Hopkins University pulled real-time data from WHO, the CDC and other government sources to track global cases of COVID-19. CLICK HERE to access this dashboard.
Who is more vulnerable to the coronavirus?
The disease does not discriminate based on race or ethnicity. People of Asian descent, including Chinese Americans, are not more likely to get COVID-19.
One group, however, appears less likely to fall ill: Children. The New York Times, citing a JAMA report, reported that few children appear to develop severe symptoms.
What's the test like?
The CDC recommends at least two swabs -- nose and throat. Samples are sent to labs that look for bits of viral genetic material, which takes roughly 4 to 6 hours. Altogether, it can take several days to ship a sample and get results back.
It's been taking two to three days, and "we are working really hard to see if we can shorten that time" by developing an in-house test, Dr. Aimee Moulin of the University of California, Davis said Thursday in a conference call held by the American College of Emergency Physicians.
Some areas have opened drive-thru sites for testing, which could reduce exposure to health workers and other patients or the public.
Can infected people who recover get it again?
It's not known. A few reports from China say some people had COVID-19, recovered and then fell ill again. It's unclear if that's a relapse, a new infection, or a case where the person never fully recovered in the first place.
Scientists at the at the Fred Hutchinson Cancer Research Center in Seattle say the 30,000-letter genetic code of the virus changes by one letter every 15 days. It's not known how many of these changes would be needed for the virus to seem different enough to the immune system of someone who had a previous version of it for it to cause a fresh infection.
Fauci told Congress on Thursday that it was unlikely that someone could get reinfected.
"We haven't formally proved it, but it is strongly likely that that's the case," he said. "Because if this acts like any other virus, once you recover, you won't get reinfected."
Will it go away in the summer?
Flu fades each spring and the new virus may do the same, Fauci said last week in a podcast with a journal editor.
"I am hoping that as we get into the warmer weather we will see a decline that will give us a chance to get our preparedness up to speed," Fauci said.
But that, too, is far from certain. "We have to assume that the virus will continue to have the capacity to spread, and it's a false hope to say yes, it will just disappear in the summertime like influenza," said Dr. Michael Ryan, the World Health Organization's emergencies chief.
Flu viruses also mutate quickly, requiring new vaccines to be made each year. If the coronavirus follows suit, Frieden said, "It could become a virus that circulates around the world for many years to come."
The Associated Press contributed to this report.