Travel restrictions, whether put in place by employers or government authorities, will severely disrupt the plans of millions of people, because during Lunar New Year hundreds of millions of Chinese move around the country to spend the holiday period with their families.
In Beijing officials have canceled all large-scale New Year celebrations "in order to control the epidemic", including the city's traditional temple fairs.
Chinese e-commerce company JD.com said in a statement that it would donate one million masks and about 60,000 medical supplies to Wuhan.
In a press conference on Thursday, WHO director general Tedros Adhanom Ghebreyesus said that of those infected, a quarter of patients have experienced severe disease, Ghebreyesus added.
Trains and planes out of Wuhan were indefinitely suspended and tollways on roads out the city were closed, leading to fear and panic for those who were trapped.
The two Wuhan residents were screened for the Wuhan coronavirus at O'Hare International Airport, Erickson said. These include Wuhan, and the nearby cities of Huanggang, Ezhou and Chibi, as well as Zhijiang, which is around 300 kilometres away.
Officials said the virus has sickened more than 800 people in China and has led to the deaths of 25 people as of Jan 23.
Didier Houssin, the chair of the emergency advisory committee, said the panel was split "almost 50-50" over whether the outbreak of the coronavirus in China amounted to a global public health emergency.
China meanwhile confirmed Thursday the first death from the virus outside the epicentre, bringing the total number of deaths to 18.
The health commission in Hebei, a northern province bordering Beijing, said an 80-year-old man died after showing symptoms on his return from a two-month stay in Wuhan to see relatives.
The other 17 fatalities have all been people aged 48 to 89 and had pre-existing health conditions, Chinese health authorities said Thursday.
The US Centers for Disease Control and Prevention (CDC) raised its travel notice to the highest level "warning" for Wuhan from level 2 to level 3, which recommends that travelers avoid all nonessential travel to the city. Nepal also confirmed its first case.
Animals are suspected to be the primary source of the outbreak, with studies published this week suggesting the virus may have originated in bats or snakes.
While the virus is moving from human to human, a situation that worries public health officials, it appears that close exposure is critical.
WHO convened its emergency committee of independent experts on Thursday to consider whether the outbreak should be declared a global health emergency, after the group failed to come to a consensus on Wednesday. However, the exact number is not yet known.
During the SARS epidemic, the Chinese government took months to report the disease and initially denied World Health Organization experts any access.
Tedros said that while WHO's role is to provide science-based recommendations, "at the end of the day, a sovereign country has the autonomy to do what it thinks is right".
WHO's emergency committee stressed the need for global vigilance and information sharing, and recommended a new meeting in "a matter of days to examine the situation further".