BEIJING (AP) — The head of a Chinese government expert team said Monday that human-to-human transmission has been confirmed in an outbreak of a new coronavirus, a development that raises the possibility that it could spread more quickly and widely.

Team leader Zhong Nanshan, a respiratory expert, said two people in Guangdong province in southern China caught the virus from family members, state media said. Some medical workers have also tested positive for the virus, the English-language China Daily newspaper reported.

The late-night announcement capped a day in which authorities announced a sharp uptick in the number of confirmed cases to more than 200, and China’s leader called on the government to take every possible step to combat the outbreak.

“The recent outbreak of novel coronavirus pneumonia in Wuhan and other places must be taken seriously,” President Xi Jinping said in his first public statement on the crisis. “Party committees, governments and relevant departments at all levels should put people’s lives and health first.”

Xi’s remarks were reported by state broadcaster CCTV on its main 7 p.m. news broadcast.

In Geneva, the World Health Organization announced it would convene an Emergency Committee meeting on Wednesday to determine whether the outbreak warrants being declared a global health crisis.

Such declarations are typically made for epidemics of severe diseases that threaten to cross borders and require an internationally coordinated response. Previous global emergencies have been declared for crises including the ongoing Ebola outbreak in Congo, the emergence of Zika virus in the Americas in 2016 and the West Africa Ebola outbreak in 2014.

The spread of the viral pneumonia comes as the country enters its busiest travel period, when millions board trains and planes for the Lunar New Year holidays. The outbreak is believed to have started late last month among people connected to a seafood market in Wuhan, a city in central China.

Wuhan health authorities said Monday an additional 136 cases have been confirmed in the city, raising the total to 198. Three have died.

Other Chinese cities also confirmed cases for the first time.

Five people in Beijing and 14 in Guangdong have been diagnosed with the new coronavirus, CCTV reported Monday evening. Seven suspected cases have been found in other parts of the country, including in Sichuan and Yunnan provinces in the southwest and in Shanghai.

Zhong said the two people in Guangdong had not been to Wuhan but fell ill after family members had returned from the city, the China Daily said.

The outbreak has put other countries on alert as millions of Chinese travel for Lunar New Year. Authorities in Thailand and in Japan have identified three cases, all involving recent travel from China.

South Korea reported its first case Monday, when a 35-year-old Chinese woman from Wuhan tested positive for the new coronavirus one day after arriving at Seoul’s Incheon airport. The woman has been isolated at a state-run hospital in Incheon city, just west of Seoul, the Korea Centers for Disease Control and Prevention said in a statement.

At least a half-dozen countries in Asia and three U.S. airports have started screening incoming airline passengers from central China.

Videos posted online show people in protective suits checking one-by-one the temperatures of plane passengers arriving in Macao from Wuhan. A man surnamed Yang who works for the Macao Health Bureau confirmed over the phone that such checks are taking place in the southern Chinese region.

Canada’s Chief Medical officer, Dr. Theresa Tam, said signs will be placed at airports in Toronto, Montreal and Vancouver in the coming days. Electronic kiosks at Customs will ask people if they have traveled to areas where coronavirus is and if they have flu like symptoms.

“The Chinese lunar year is coming so out of abundance precaution that’s why we are putting out additional information for travelers,” Tam said.

Many of the initial cases of the coronavirus were linked to a seafood market in Wuhan, which was closed as authorities investigated.

Since hundreds of people who came into close contact with diagnosed patients have not gotten sick, the municipal health commission maintains that the virus is not easily transmitted between humans.

“However, the source of the new type of coronavirus has not been found, we do not fully understand how the virus is transmitted, and changes in the virus still need to be closely monitored,” China’s National Health Commission said in a statement Sunday.

Coronaviruses cause diseases ranging from the common cold to SARS, or severe acute respiratory syndrome. SARS first infected people in southern China in late 2002 and spread to more than two dozen countries, killing nearly 800. The Chinese government initially tried to conceal the severity of the SARS epidemic, but its cover-up was exposed by a high-ranking physician.

“In the early days of SARS, reports were delayed and covered up,” said an editorial in the nationalistic Global Times. “That kind of thing must not happen again in China.”

“We have made great strides in medicine, social affairs management and public opinion since 2003,” the editorial said.

Xi instructed government departments Monday to promptly release information on the virus and deepen international cooperation.

China has notified and maintained close communication with the World Health Organization and other relevant countries and regions, Chinese Foreign Ministry spokesman Geng Shuang said at a regular news briefing.

Wuhan has also adopted measures to control the flow of people leaving the city, Geng said.

Initial symptoms of the novel coronavirus include fever, cough, tightness of the chest and shortness of breath, and those seriously ill developed pneumonia.

On the Weibo social media platform, which is widely used in China, people posted prevention advice such as wearing masks and washing hands. Some people said they had canceled their travel plans and were staying home for Lunar New Year.

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Associated Press researcher Yu Bing in Beijing, writer Hyung-jin Kim in Seoul, South Korea, and writer Rob Gillies in Toronto contributed to this report.