More than 7,700 people have been infected with the virus - nearly all of them in China - and 170 have died.
The WHO had initially downplayed the threat posed by the disease, but revised its risk assessment after crisis talks on Thursday.
"Over the past few weeks, we have witnessed the emergence of a previously unknown pathogen which has escalated into an unprecedented outbreak", World Health Organization director-general Tedros Adhanom Ghebreyesus said on Thursday when he announced the emergency declaration. "Although these numbers are still relatively small compared to the number of cases in, we must all act together now to limit further spread". Dr. Christina Madison with Roseman University says this declaration would help get resources to countries that don't have health systems to cope with the disease.
The Wuhan virus has spread to 23 countries, and has taken 213 lives in the weeks since the outbreak started in Wuhan, a city the size of London in the middle of China.
About 100 cases have been reported in at least 18 other countries, with no deaths outside China. They are tested and monitored at a military base in southern California.
China extended its Lunar New Year holiday to Sunday to try to keep people home, but the wave of returning travelers could potentially cause the virus to spread further.
The government on Thursday reported 38 new deaths in the preceding 24 hours, the highest one-day total since the virus was detected late past year.
All however one of many new deaths had been in Hubei.
Taxi drivers in protective suits are seen in front of a residential area, following an outbreak of the new coronavirus and the city's lockdown, in Wuhan, Hubei province, China January 28, 2020. Another 81,000 folks had been beneath commentary for attainable an infection.
The pathogen is believed to have emerged in a market that sold wild game, and spread during a Lunar New Year holiday season in which hundreds of millions of Chinese travel at home or overseas.
Thousands of foreigners have been trapped in Wuhan since it was sealed off last week.
A French airplane was additionally as a result of depart Wuhan on Friday, in accordance with an AFP journalist on the scene.
The new virus has now infected more people in China than were infected during the 2002-2003 SARS epidemic, a cousin of the new virus.
Two of the three infected passengers showed no symptoms, underscoring the difficulty detecting the coronavirus.
Compounding fears, Japan was permitting the arrivals - greater than 400 have been repatriated after a second flight on Thursday - to "self-quarantine".
In contrast, other countries organising evacuations said they were all planning to quarantine.
Some experts question whether the new virus shares similarities with seasonal flu, which has a low mortality rate but infects so many people that more than half a million may die from it each year, according to global health estimates. That outbreak also began in China and eventually killed almost 800 people worldwide in 2002-03.
Major airlines that have suspended or reduced service to China include British Airways, German flag carrier Lufthansa, American Airlines, KLM and United.
Chinese efforts to halt the virus have included the suspension of lessons nationwide and an extension of the Lunar New Year vacation.
All soccer matches throughout the nation additionally will likely be postponed, the Chinese Football Association stated, together with video games within the top-tier Chinese Super League.
It's now a "global health emergency".
In the wake of numerous airlines cancelling flights to China and businesses including Starbucks and McDonald's temporarily closing hundreds of shops, Tedros said World Health Organization was not recommending limiting travel or trade to China. Tedros Adhanom Ghebreyesus made the announcement on Thursday evening.
"It's definitely very challenging, but we're confident we can exert effective control", Wu told reporters at the briefing.
Throughout China, signs of paranoia multiplied, with residents of some Beijing residential compounds erecting makeshift barriers to their premises.
In considered one of many related images posted on-line, a person sporting a surgical masks and brandishing a conventional martial arts weapon squatted on a barricade outdoors a Chinese village, close to an indication saying: "Outsiders forbidden from entering".