The U.S. and Japan advised citizens to avoid traveling to China, hours after the World Health Organization declared the coronavirus outbreak a global health emergency. Cases around the world have now risen to more than 9,800, surpassing the number officially reported during the SARS epidemic.

The WHO declaration that the outbreak was a public health emergency of international concern will let public health authorities aid countries with less-robust health systems to stop the spread of the virus.

WHO Director-General Tedros Adhanom Ghebreyesus praised China‘s efforts to contain the outbreak, saying he had never seen a nation respond so aggressively to a disease, including building a new hospital in just 10 days. It’s a contrast to the criticism China faced for a lack to transparency during SARS. 

Tedros said there’s no need at this time for measures that interfere with travel and trade, even though many governments, airlines and businesses have already taken such steps.

The coronavirus was spreading from person to person earlier than reported, according to a study by Chinese scientists.

Among 47 cases that occurred during 2019, 14 had been in contact with another person with respiratory symptoms, indicating likely human-to-human transmission, researchers from the Chinese Center for Disease Control and Prevention said in a study published Jan. 29 in the New England Journal of Medicine. Their analysis of the first 425 cases in the city of Wuhan found that in its early stages, the epidemic doubled in size every 7.4 days.

“There is evidence that human-to-human transmission has occurred among close contacts since the middle of December,” Qun Li and colleagues said. Official confirmation of such transmissions wasn’t reported until weeks later.

The total number of coronavirus cases around the world has reached more than 9,800. That tops the count from the SARS epidemic, which also originated in China and in 2003 saw 8,096 officially reported cases, according to the WHO.

The latest tally shows the speed with which the new virus has spread in a short period of time, from the first case in December. It’s reached the same level that the SARS epidemic did during its span of about eight months.

The numbers come with a footnote, however. SARS cases were widely considered to be under-reported, as possibly thousands went undocumented in the first few months. At the same time, the official count for the current virus is likely to be below the actual number of cases, as health officials scramble to widen testing.

In Luxembourg, the government has urged cancelling any non-essential travel to China but said it was unlikely that the virus would be brought back to the country by travellers from the region. Luxembourg’s all-cargo airline has distributed personal masks and disinfection tissues to fight germs and temporarily stopped transporting live animals from China, Cargolux spokeswoman Moa Sigurdardottir said. Cargolux has 15 aircraft landings and take-offs per week in the key economic and transportation city of Zhengzhou, about 500 kilometres from Wuhan.

Japan moved to strengthen its travel warning for China and to bar patients infected with the new coronavirus from entering the country, after criticism that its initial response to the deadly outbreak was too lax.

The government is set to advise that non-urgent trips to China should be canceled. It also plans to bring forward an order allowing compulsory hospitalization to Feb. 1, earlier than Feb. 7 as originally planned, Prime Minister Shinzo Abe told parliament. Virus patients will be barred from entering the country from the same date, he added.

Tensions are rising across the region as governments bring their citizens home from the outbreak epicenter in China, risking greater exposure among domestic populations.

Australia plans to isolate its evacuees from Wuhan on Christmas Island, better known for its grim history as a detention center for would-be asylum seekers, while the U.S. flew its citizens from the virus-stricken Chinese city to an isolated military base in California.

The U.S. State Department on Thursday night warned Americans against travel to China. “Those currently in China should consider departing using commercial means,” the department said in the advisory, which was Level 4, the most severe travel warning category. The Level 4 advisory puts China among several nations that the U.S. warns its citizens to avoid, including North Korea, Venezuela, Iran and Somalia.

The global cost of the coronavirus could be three or four times that of the 2003 SARS outbreak that sapped the world’s economy by $40 billion, according to the economist who calculated that figure.The sheer growth in the Chinese economy over the last 17 years means the global health emergency triggered by the coronavirus outbreak has far greater potential to gouge global growth, according to Warwick McKibbin, professor of economics at the Australian National University in Canberra.

©2020 Bloomberg L.P.