Two patients in Zhuhai, Guangdong province, with pneumonia caused by a new strain of coronavirus had close contact with the same family member who had been in Wuhan, Hubei province-the focal point of the recent outbreak-strongly suggesting human-to-human transmission of the virus.

A 76-year-old woman, whose husband had traveled from Wuhan by train, and their 49-year-old daughter showed symptoms including fever. The man had fallen ill after arriving on Jan 11. He sought medical treatment on Jan 15.

The father was diagnosed with the new strain of coronavirus and was admitted to the Fifth Affiliated Hospital of Sun Yat-sen University two days later. The mother and daughter were transferred from medical observation to quarantine.

The three were in stable condition, according to a statement issued on Monday by the Zhuhai health bureau.

Fifteen medical workers have been infected in Wuhan, and those cases also point to human-to-human transmission, said Zhong Nanshan, head of a high-level expert team organized on Monday by the National Health Commission. Zhong spoke at a news conference in Guangzhou on Tuesday.

Quarantining infected people is the most effective way to control the spread of the virus, and close monitoring of anyone who had close contact with an infected person is extremely important, Zhong said.

The risk of transmission through a community exists, but the risk of a major outbreak that way is not high, said He Jianfeng, chief expert of the Guangdong Provincial Center for Disease Control and Prevention.

Imported cases are expected to increase during Spring Festival family reunions, He said, advising people going to and coming from Wuhan to wear masks, monitor their health and see a doctor quickly if symptoms emerge.

People in Guangdong need not panic, as a well-established medical treatment system is in place, He said.

Meanwhile, 13 new cases of pneumonia caused by the virus were confirmed in Guangdong on Monday, bringing the total to 14 in the province as of 3 pm on Tuesday, said Zhang Guangjun, vice-governor of the province. Nine of those cases had been reported in Shenzhen, three in Zhuhai, one in Zhanjiang and one in Huizhou.

Nine of the patients were male. Nine people of the total were over 60 years old and one was a 10-year-old child.

Twelve of the patients had lived or traveled in Wuhan, where the first cases were reported. Four of the patients were in serious condition and two were in critical condition.

People who had close contact with the patients have been checked, and no abnormal conditions have been found, Zhang said.

An emergency command mechanism for suppressing an outbreak was established immediately after the first cases were confirmed in Guangdong on Jan 14. A team led by provincial Party secretary Li Xi was set up on Tuesday.

Body temperature monitoring has started at public venues, including airports, railway stations and bus terminals in Guangdong on Tuesday.

Cooperation mechanisms for disease control between Guangdong, Hong Kong and Macao have been in place since 2003, and those three places have been actively communicating during the current outbreak, said Duan Yufei, director of the Guangdong health commission.

China has vowed transparency with information about the virus and its effects, said Zhong, the expert team's head, adding that cooperation has been good between Guangdong, Hong Kong and Macao at the government and technical levels.