BEIJING—A leading Chinese health official said that a newly identified virus originating in central China has spread between humans, confirming a chief concern of authorities as the disease is transmitted around the country and across Asia, infecting more than 150 new patients.

The prospect of human-to-human transmission of the coronavirus, which causes a potentially deadly pneumonia that already has claimed three lives, is likely to raise fresh concern as tens of millions of Chinese citizens crisscross the country this week for the annual Lunar New Year holiday, the busiest travel period of the year.

Zhong Nanshan, one of China’s most highly-regarded epidemiology experts, urged heightened vigilance in a live interview on state broadcaster China Central Television Monday, citing the risk of human-to-human transmission.

“Right now is the time when we should increase alert,” said Dr. Zhong, who rose to national prominence nearly two decades ago as an authoritative voice during China’s fight against severe acute respiratory syndrome, or SARS. In that outbreak, a similar coronavirus killed 774 people after its emergence in southern China beginning in late 2002.

The new warnings came on a day when the number of confirmed cases of the new coronavirus more than tripled to 218, according to Chinese state media and health authorities, including in Beijing, Shanghai and the southern metropolis of Shenzhen—three of the country’s biggest and most affluent cities. It also appeared in South Korea for the first time.

Dr. Zhong, who is leading an expert committee on the outbreak for China’s cabinet-level National Health Commission, said 14 medical staff involved in treating the new coronavirus have themselves been infected with the disease. It’s unclear whether these medical staff members were included in the reported patient figures.

Yang Gonghuan, the former deputy head of the Chinese Center for Disease Control and Prevention, said in a separate interview with the China Business Journal newspaper Monday that human-to-human transmission of the disease had occurred.

Earlier Monday, the World Health Organization said the spread of the disease was likely the product of “some limited human-to-human transmission occurring between close contacts.”

The sudden spread of the disease is likely to spark questions over the transparency of disclosures by Chinese health authorities.

President Xi Jinping earlier Monday urged authorities to make efforts to prevent and control the spreading infection, according to the state-run Xinhua News Agency. Officials should “release outbreak information in a timely manner and deepen international cooperation,” he said.

China is working with other countries to prevent and control the outbreak, Chinese Foreign Ministry spokesman Geng Shuang said at a regular media briefing in Beijing on Monday. “We’ve formulated prevention and control plans, treated patients, monitored their close contacts, conducted epidemiological research and released information in a timely matter,” he said.

South Korean authorities said Monday that a 35-year-old Chinese woman who had flown into the country from the central Chinese city of Wuhan, where the outbreak first occurred, had contracted the coronavirus.

The previous three patients who have been identified outside China—two Chinese tourists in Thailand and a man from Japan—had all traveled from the Wuhan area.

In the U.S., where no cases have so far been detected, the Centers for Disease Control and Prevention and Department of Homeland Security’s Customs and Border Protection have begun screening people traveling from Wuhan for fevers, coughs or difficulty breathing.

Health authorities in Wuhan, a densely populated city of 19 million people, said Monday that the number of patients infected with the new coronavirus jumped to 198, from 62 on Sunday. The statement said 35 of those cases were severe, while nine were critical.

The death of a third infected patient occurred over the weekend, Wuhan authorities said Monday, without offering details. In the case of the two earlier fatalities, authorities had previously said the men suffered from existing illnesses.

The overall count of confirmed cases doesn’t include suspected cases that have sprung up in a number of Chinese provinces, including Shandong on the east coast, Sichuan in the interior and Yunnan and Guangxi on the southwestern border with Vietnam, according to CCTV’s report Monday. Separately, five suspected cases were reported by health authorities in coastal Zhejiang province, just south of Shanghai on the country’s east coast.

Dina Amelia Kalmeta is the Founder and CEO of Your New Life in Christ Ministries - CWW7NEWS. Dina reports on world events as they pertain to Bible Prophecy. Before Your New Life in Christ Ministries, Dina served as a Leader for INCHRIST NETWORK leading teams online and spreading the Gospel of Jesus Christ. Her mission today is to bring hard evidence that what is taking place in the world isn't just coincidence, but indeed proof that the last days the Bible warned us about are upon us right now.