The World Health Organization on Thursday declined to categorize the coronavirus sweeping across China as a global health emergency, saying there is no evidence of human-to-human infection outside China.

Hours after the organization made the decision, China announced that eight more people had died from the virus, bringing the number to 25. Among them was a death outside the Chinese central province of Hubei where the virus had previously remained in containment.

The health commission in Hebei, a northern province bordering Beijing, said an 80-year-old man died after showing symptoms upon his return from a two-month stay in Wuhan to see relatives. Wuhan is the capital of Hubei and has been the epicenter of the outbreak of the coronavirus first detected last month.

Chinese authorities Thursday moved to lock down at least three cities with a combined population of more than 18 million in an unprecedented effort to contain the virus during the busy Lunar New Year travel period.

Didier Houssin, who chaired an emergency WHO committee, said very few cases have been diagnosed outside China, which he credited to the aggressive work to contain the outbreak.

The panel, which Houssin said was divided almost evenly on the issue, made its recommendation to WHO Director-General Tedros Adhanom Ghebreyesus.

"The advice to the director-general provided by the emergency committee is that now is not the time," Houssin said. "It's too early."

More than 800 people in China have been diagnosed with the virus. A small number of cases have been diagnosed in other countries, including one case in the U.S.

Tedros, who made the final decision, said WHO is "following the outbreak every minute of every day" and could decide to declare a public health emergency of international concern, or PHEIC.

Such declarations can result in more resources made available to combat outbreaks but also can spur restrictions on trade and travel.

"This should not be taken as a sign that WHO does not think the situation is serious or that we’re not taking it seriously," Tedros said.

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In the U.S., airports in New York, Chicago, Los Angeles, Atlanta and San Francisco stepped up health checks for passengers arriving from China.

In Boston, at least nine people were screened for the virus at Logan International Airport but were cleared and allowed to continue to final destinations. In Los Angeles, an American Airlines passenger arriving from Mexico City was transported to a medical center as a precaution.

"We don't want the American public to be worried about this because their risk is low," says Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases. "On the other hand, we are taking this very seriously and are dealing very closely with Chinese authorities."

China suspended planes, trains and ferries in and out of three cities with a combined population of almost 20 million people. Public transport has been mostly suspended within Huanggang, Ezhou and Wuhan, the city of 11 million serving as the epicenter for the virus.

Fauci compared the outbreak with severe acute respiratory syndrome, SARS, a coronavirus that killed more than 600 people across mainland China and Hong Kong along with more than 100 other people around the world in 2002-2003. Fauci said a vaccine was developed for SARS but was not needed.

"SARS essentially disappeared because of very good public health practices," he said. "The question of developing a vaccine is not a major issue."

What is coronavirus? What are the symptoms?

Coronaviruses are a large family of viruses that cause illness ranging from the common cold to pneumonia. Common signs of infection include fever, cough, shortness of breath and breathing difficulties. In more severe cases, infection can cause severe acute respiratory syndrome, kidney failure and death.

What is the threat to Americans?

Health officials said the virus, which probably spreads through tiny droplets when a person coughs or sneezes, is low-risk. Officials urged people to take the usual cold and flu season precaution: frequent hand washing, covering your mouth when coughing or sneezing and staying home when you don't feel well. "These illnesses can pop up anywhere," said Trish Perl, chief of infectious diseases at UT Southwestern Medical Center in Dallas. "This is a dynamic situation that can dramatically change from day to day."

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Are other nations taking precautions?

Airports around the world stepped up health screenings. Dubai International Airport, the world’s busiest for international travel, said all passengers arriving on direct flights from China will receive health screenings. Russian airports screen passengers arriving from China. British authorities said passengers arriving from China to Heathrow Airport in London, Europe’s busiest, and other airports won't get special screening but will be given information leaflets on what to do if they become ill.

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When, where did it come from?

Coronaviruses are zoonotic, meaning they are transmitted between animals and people. Many of the initial cases were linked to a seafood and meat market in Wuhan. Chinese health officials, which first reported the cases last month, said human-to-human transmission has been confirmed.

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How is China grappling with the problem?

President Xi Jinping said curbing the outbreak and saving lives are top priorities. The timing of the outbreak could not be worse – the Lunar New Year is Saturday, and hundreds of millions of people across Asia travel in packed buses, trains and planes bound for celebrations. Beijing canceled its major new year events and announced The Forbidden City, the palace complex/museum, will close indefinitely Saturday. Hong Kong turned two holiday camps into quarantine areas for people who may have come into contact with the virus.

Contributing: The Associated Press