But the measures have yet to pay dividends, with the government reporting 38 new deaths in the 24 hours to Thursday, the highest one-day total. Of the new deaths, 37 were in Hubei province, of which Wuhan is the capital, and one was in the southwestern province of Sichuan. With a case confirmed in Tibet, it has now spread to every corner of the country.
Singapore's foreign ministry said it was returning 92 Singaporeans from Wuhan on January 30. Reports said nine of those aboard the flight showed signs of cough and fever.
Nancy Messonnier, MD, director of the CDC's national center for immunization and respiratory diseases, said Thursday in a press call that the case centers on a married couple in Chicago.
The United States and the UK have given would-be travellers similar warnings.
Countries around the world have already moved to limit personal travel to and from China in the wake of the outbreak, including Australia, which is urging citizens to "reconsider [their] need to travel" there while the outbreak is ongoing.
But at a news conference earlier this week, the US government's infectious diseases chief, Dr. Anthony Fauci, said outbreaks are not driven by that kind of spread.
It cited Ministry of Commerce data showing current reserves in Wuhan can ensure a secure supply of rice and cooking oil for more than 15 days, pork and eggs for more than 10 days and vegetables for about five days.
Concern is also growing that thousands of Chinese factory workers on Lunar New Year holidays may struggle to get back to work next week, due to extensive travel restrictions imposed to stop the spread of the virus. Another 81,000 people were under observation for possible infection. It can also spread via contaminated surfaces such as door handles or railings.
The WHO emergencies chief, Michael Ryan, spoke in Geneva after returning from Beijing.
Ghebreyesus applauded the Chinese government's "speed" in which it "detected the outbreak, isolated the virus, sequenced the genome and shared it with World Health Organization", and said China set "a new standard for outbreak response".
To date, about 99% of the cases are in China. There have been more than 8,200 cases diagnosed globally; the vast majority have been in China, where 170 deaths have been recorded.
Most cases have emerged in people who have travelled from the Chinese city of Wuhan, where the outbreak began.
It's not known whether anyone who is infected but not showing symptoms can spread the virus. The new virus is from the coronavirus family, which includes those that can cause the common cold as well as more serious illnesses such as SARS and MERS.
"However", he continued, "the full picture of how easy and how sustainable this virus can spread is unclear".
There now have been 98 cases of the virus outside of China - including eight cases of human-to-human transmission in four countries: Germany, Japan, Vietnam and the U.S., World Health Organization confirmed, adding that there have been no deaths outside of China.
There are concerns that China's economy could be negatively impacted by a PHEIC determination.
However, the response of the United Nations body to the disaster has been criticised in a number of reports.
The government has classified the new virus a "designated infectious disease", meaning it will be able to forcibly hospitalise those who test positive, but only once the regulation takes effect from February 7.