"However, the detection of three cases outside China is worrying".
"There might be more cases, but we really need to wait for our colleagues in China to complete their investigation", Messonnier said.
Checks in Thailand will be especially rigorous, health authorities said, as there are a total of eight direct flights a day from Wuhan, the epicentre of the outbreak, to Bangkok, Phuket and Krabi, as well as flights every other day to Chiang Mai.
The Public Health Agency of Canada says additional measures will include messaging on arrivals screens at the Toronto, Montreal and Vancouver worldwide airports reminding travellers from Wuhan to inform a border service officer if they are experiencing flu-like symptoms. It has also been reported that the Health Ministry is monitoring the situation in India in collaboration with WHO.
While the overall risk to people in the United States is low, "we know it's crucial to be proactive and prepared", Dr. Nancy Messonnier, the director of CDC's National Center for Immunization and Respiratory Diseases, said on a call with reporters.
Though the government advisory said only one person had died after contracting virus, according to media reports two people have died - both in Wuhan.
But a paper published on Friday by scientists with the MRC Centre for Global Infectious Disease Analysis at Imperial College in London said the number of cases in the city was likely closer to 1,700. One travel-related case each has been reported in Thailand and Japan. The full report was not available, however.
December 31 2019: The WHO China Country Office was informed of cases of pneumonia of unknown cause detected in Wuhan City, Hubei Province of China.
Thailand detected its second case of a mysterious SARS-linked virus in a visitor from China, health officials said Friday, as authorities ramp up airport screenings ahead of an expected surge in arrivals for Chinese New Year. A different coronavirus caused the SARS outbreak in China in 2003 which killed almost 800 people and also MERS, another severe respiratory ailment that has been present in Saudi Arabia and other Middle Eastern countries since 2012.
Coronaviruses are a large family of viruses that can cause infections ranging from the common cold to SARS. It is not clear if the virus is now capable of human-to-human transmission, but CDC officials say there are some indications that people may be able to spread the virus in a limited way.
Officials in China have linked the viral infections to a Wuhan seafood and wildlife market, which has been closed since January 1 to prevent further spread of the illness.
The health agency said that the new procedures will be implemented on all passengers arriving at the airports of San Francisco (SFO), New York (JFK), and Los Angeles (LAX), which receives the highest number of travelers from Wuhan.
In Singapore, temperature screening measures have been put up at Changi Airport for inbound flights from Wuhan and suspected cases will be referred to hospitals for further assessment.