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). It is being called the 2019 novel coronavirus or 2019-nCoV.

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.

3-D illustration of a coronavirus Chinese scientists say the new virus is a never-before-discovered coronavirus, which is in the same family as the one illustrated here. (Photo: Kateryna Kon/Shutterstock)

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

Where did it come from?

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.

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 report is still in its early stages and more research must be done, the researchers 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."

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 on Jan. 17, 2020 in Wuhan, China. (Photo: Getty Images)

So far, at least 26 people have died in China from the coronavirus. Since the virus was first detected on Dec. 12, more than 800 cases of the virus have been diagnosed, Reuters reports.

Outside of mainland China, other cases have been reported in Thailand, Japan, South Korea, Taiwan, Vietnam, Macao, Hong Kong and Singapore, reports CNN.

The first case in the U.S. was confirmed by the CDC on Jan. 21 in Washington state. A second case was confirmed in Chicago on Jan. 24. Both patients had returned to the U.S. after visiting Wuhan.

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 63 potential cases in 22 states; so far, 11 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?

Chinese officials now confirm that the virus can spread from person to person. At least two people have become ill despite living hundreds of miles away from Wuhan.

"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 was not as strong as SARS, but that it was "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."

China announced Friday that it is building a 1,000-bed hospital for patients infected with the virus, reports the Associated Press. The facility will be modeled after a hospital built in six days in Xiaotangshan for SARS patients. The Wuhan hospital is slated to be completed by Feb. 3.

Three separate research teams are working to develop potential vaccines against the virus, according to the Coalition for Epidemic Preparedness Innovations (CEPI) (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, on Jan. 18, 2020. (Photo: David McNew/Getty Images)

The outbreak comes as China prepares for the Lunar New Year holiday. During this time, millions of people typically travel throughout the country and abroad.

Around the world, airports have tightened screenings of travelers coming from China. In the U.S., the CDC announced enhanced health screenings at five airports that receive most of the travelers from Wuhan: San Francisco (SFO), New York (JFK), Los Angeles (LAX), Chicago (ORD) and Atlanta (ATL) airports.

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 in order to attempt to curb the spread of the epidemic, The New York Times reports. Travel restrictions are also in place in 12 cities in central China’s Hubei province, according to the AP.

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

WHO called an emergency two-day meeting on Jan. 22-23 to consider declaring a "public health emergency of international concern." The members ultimately decided it was not yet a global health emergency.

“Make no mistake, this is now an emergency in China, but this has not yet become a global health emergency,” said Dr. Tedros Adhanom Ghebreyesus, director-general of the WHO in a news conference.

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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