A mysterious pneumonia outbreak in China may be linked to a virus that has never been seen before. Chinese scientists have identified the virus as a new type of coronavirus, reports the World Health Organization (WHO). After being called the 2019 novel coronavirus or 2019-nCoV for weeks, the virus was officially named COVID-19 by the WHO in mid-February.

Most coronaviruses cause mild to moderate symptoms like the common cold, according to the Centers for Disease Control and Prevention (CDC). But coronaviruses are the same family of viruses that include severe acute respiratory syndrome (SARS) and the Middle East respiratory syndrome (MERS).

SARS was first recognized in China in November 2002. It killed 774 of the 8,098 people infected, according to the CDC. It spread to more than two dozen countries including the U.S. and Canada before it was contained.

"There is a strong memory of SARS, that's where a lot of fear comes from, but we're a lot more prepared to deal with those types of diseases," Dr. Josie Golding, from the Wellcome Trust, a London-based research charity, tells the BBC.

The coronavirus COVID-19 in yellow is seen emerging from cells (blue and pink) cultured in a lab. This scanning electron microscope image shows coronavirus COVID-19 in yellow emerging from cells (blue and pink) cultured in a lab. (Photo: NIAID-RML [CC BY 2.0]/Flickr)

Researchers are still working to learn more about the mysterious illness. Here's what we know so far.

Where did it come from?

This image from the CDC depicts the 2019 novel coronavirus This image from the CDC depicts the 2019 coronavirus. The spikes along the outer surface of the virus give it its crown, or corona. (Photo: CDC)

The strain has been linked to a seafood market in Wuhan, China, that has been closed for sanitation since Jan. 1. Local media outlets have reported that the market also sold snakes, marmots, monkeys and other animals. This sparked concerns that the virus was transmitted from animals to humans.

Li Wenliang, a doctor working in Wuhan, was one of the first to warn about the coronavirus outbreak on Dec. 30. Silenced by the police, he later became infected with the virus and died, according to The New York Times.

Researchers are trying to determine the origin of the virus. Some scientists have used samples of the virus to determine its genetic code and believe it may have originated from snakes. After analyzing protein codes favored by this coronavirus and comparing them to protein codes from other animals, they found that the codes were most similar to those in snakes. Specifically, the Chinese krait and the Chinese cobra may have been the source of the virus, researchers suggest.

The research is still in its early stages and more work must be done, the scientist write in The Conversation.

"Sampling viral RNA from animals sold at the market and from wild snakes and bats is needed to confirm the origin of the virus. Nonetheless, the reported findings will also provide insights for developing prevention and treatment protocols," they wrote.

Meanwhile, other scientists have raised questions about the theory. Other researchers suggest that this coronavirus is a close match to one that is known to live in bats. Bats are known to carry and spread many viruses — such as rabies, Ebola, SARS and Nipah — without getting sick themselves, points out Scientific American.

“We don’t know the source yet, but there’s pretty strong evidence that this is a bat origin coronavirus,” Dr. Peter Daszak, president of EcoHealth Alliance, who has been studying zoonotic diseases in China for 15 years, told The New York Times. “It’s probably going to be the Chinese horseshoe bat."

All researchers agree these are early days in the investigation.

Is it serious?

Medical staff transfer patients to Jin Yintan hospital on Jan. 17, 2020 in Wuhan, China. Medical staff transfer patients to Jin Yintan hospital in January 2020 in Wuhan, China. (Photo: Getty Images)

So far, at least 1,384 people have died from the coronavirus including a 60-year-old U.S. citizen in Wuhan. Few details of the American's death have been released. Since the virus was first detected in China on Dec. 12, more than 64,000 cases of the virus have been diagnosed. That's more than the 774 deaths and about 8,000 cases diagnosed during the 2003 SARS outbreak

Recently, two newborn babies were infected in China, reports CNN. It may be a case where the mothers infected the child in utero or they were exposed through handling by an infected health care work or handling or breastfeeding by the mother.

Infectious disease experts are saying that the coronavirus is likely to become a pandemic, reports The New York Times. A pandemic is the worldwide spread of a new disease, according to WHO.

“It’s very, very transmissible, and it almost certainly is going to be a pandemic,” said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Disease. “But will it be catastrophic? I don’t know.”

The WHO, however, says it is currently not a pandemic.

"We are not in a pandemic," said Sylvie Briand, director of the Infectious Hazards Management Department at the WHO, in a media conference, explaining that the virus is currently considered an epidemic with multiple locations. "We will try to extinguish the transmission in each of these."

This image shows the new coronavirus in orange. The virus was isolated from a patient in the U.S. This image shows the new coronavirus in orange. The virus was isolated from a patient in the U.S. (Photo: NIAID-RML [CC BY 2.0]/Flickr)

Outside of mainland China, cases have been reported in more than two dozen international locations. This real-time tracking map from Johns Hopkins University's Center for Systems Science and Engineering monitors confirmed cases globally. There have been two deaths outside of mainland China: one in the Philippines and one in Hong Kong.

The U.S. has 15 confirmed cases of the virus. Two of the cases involve person-to-person transmissions where people traveled to Wuhan and then apparently passed the diseases to their spouses, ABC News reports.

There have been eight confirmed cases in California, two in Illinois and one each in Massachusetts, Arizona, Wisconsin, Texas and Washington.

The risk to the U.S. public remains low but "the situation is evolving rapidly" with more cases likely to be confirmed in coming days, said Nancy Messonnier, the director of the National Center for Immunization and Respiratory Diseases at the CDC, in a press briefing. The CDC is investigating 443 potential cases in 42 states; so far, 347 have tested negative.

The main symptom is fever, according to WHO, with some patients reporting difficulty breathing and X-rays showing some lung lesions.

How fast is it spreading?

A woman wearing a protective mask rides a motorized bike on an empty road in Wuhan, China. A woman wearing a protective mask rides a motorized bike on an empty road in Wuhan, China. (Photo: Getty Images)

Health officials say the virus can spread from person to person. Several people have become ill despite living hundreds of miles away from Wuhan. China's health minister Ma Xiaowei said people can spread the virus before they have symptoms, according to CNN. It's harder to control a virus if people are spreading the disease before they even know they have it.

"The current cases show there is definitely human-to-human transmission," respiratory expert Zhong Nanshan, head of the team set up by China's National Health Commission to investigate the virus told Chinese state-run CCTV, reports CNN.

Zhong, who helped discover SARS, said the infectiousness of this particular virus is not as strong as SARS, but that it is "climbing" and the "death rate at the moment is not so representative."

Said the CDC in a media release: "While originally thought to be spreading from animal-to-person, there are growing indications that limited person-to-person spread is happening. It’s unclear how easily this virus is spreading between people."

The CDC has developed a rapid diagnostic test for the virus but it can only be used at the agency. So state health organizations have to send samples to the CDC's lab for testing. The agency hopes to quickly develop a test that can be used by other health care organizations on site, Messonnier said in a Jan. 28 media conference.

Two new hospitals were built in Wuhan for patients infected with the virus, reports CNN. They were opened by the first week of February. The facilities were modeled after a hospital built in six days in Xiaotangshan for SARS patients, reports the Associated Press.

Three separate research teams are working to develop potential vaccines against the virus, according to the Coalition for Epidemic Preparedness Innovations (CEPI). Typically it can take as long as a decade to develop new vaccines, but the hope is to get a vaccine for this virus in trials by June and approved for use in a year, Reuters reports.

How worried are people?

woman arriving airport with mask A woman arriving on an international flight to Los Angeles International Airport wears a mask on the first day of health screenings for coronavirus of travelers from Wuhan, China, in January 2020. (Photo: David McNew/Getty Images)

The outbreak comes during the Lunar New Year holiday. During this time, millions of people typically travel throughout the country and abroad. In an effort to contain the disease, the Chinese government extended the holiday to Feb 2, and some municipalities are extending it even longer. Some factories and companies are open for business again with rules varying from city to city, reports The New York Times. Some are requiring managers to bar workers who have traveled near Wuhan recently; others are requiring employees to have their temperatures taken regularly.

Around the world, airports have tightened screenings of travelers coming from China. In the U.S., the CDC originally announced enhanced health screenings at five airports that receive most of the travelers from Wuhan, but announced on Jan. 28 that they would expand screenings to 20 airports that receive many passengers from China.

Several airlines have cut the number of flights they are operating to China or are canceling all of them completely, reports CNN.

“Right now, there is no spread of this virus in our communities at home,” said Dr. Robert Redfield, director of the CDC, at a news briefing. “The coming days and weeks are likely to bring more cases including the possibility of person-to-person spread. Our goal is to contain this virus and prevent sustained spread of the virus in our country.”

The U.S. state department advised against all travel to China and told Americans in China to consider departing using commercial means.

More than 60 countries have placed some sort of immigration control on Chinese citizens, either tightening visa rules, restricting entry or increasing health checks as they enter the country, reports CNN.

Social media is full of images of people standing in long lines to buy face masks, Reuters reports, with some vendors limiting sales as demand surges. In Shanghai, city officials warned that they would punish those who hoard masks that could help prevent the illness from spreading.

Wuhan has shut down public transportation, canceling planes and trains, as well as temporarily suspending bus, subway and ferry service to attempt to curb the spread of the epidemic, The New York Times reports. Travel restrictions and partial lockdowns are also in place in at least 15 cities, affecting almost 60 million people, according to CNN.

Part of the Great Wall, Shanghai Disneyland and Beijing's Forbidden City are many other places have been closed indefinitely.

On Jan. 30, WHO declared a "public health emergency of international concern." Members had decided a week earlier that it was not yet a global health emergency. But the rising numbers of cases, evidence of some person-to-person transmission and the spread to more countries caused the group to reconvene.

"The main reason for this declaration is not because of what is happening in China, but because of what is happening in other countries," said Dr. Tedros Adhanom Ghebreyesus, director-general of the WHO, in a statement. "Our greatest concern is the potential for the virus to spread to countries with weaker health systems, and which are ill-prepared to deal with it."

Editor's note: This story has been updated with new information since it was published in January 2020.

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.

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