As the death toll and infection numbers climb, international health officials struggle to make sense of sparse data on the coronavirus from China.

A new virus that originated in China has all the marking of a global crisis: It emerged suddenly and can kill people. Its crossed borders easily, and requires immediate, coordinated efforts between countries to contain it. The details taken together seem enough for the World Health Organization to declare an international public health emergency. But on Wednesday, the WHO demurred.
After several hours of closed-door meetings, the 16-person panel of independent experts tasked with advising WHO leadership on the issue took a vote and found themselves split down the middle. WHO Director-General Tedros Ghebreyesus told reporters he has asked the emergency committee to meet again tomorrow to continue the discussion. This is an evolving and complex situation, he said. The decision about whether or not to declare a public health emergency of international concern is one I take extremely seriously, and one I am only prepared to make with appropriate consideration of all the evidence.
Three weeks ago, Chinese authorities alerted the WHO that it was experiencing a cluster of mysterious pneumonia cases. Since then, the world has learned that a new virus that jumped from animals into people and is now spreading between humans is behind the outbreak. Over the past few days the number of cases in China has spiked from dozens to more than 500, including 17 deaths. Cases have now been confirmed in Thailand, Japan, South Korea, and the US. But thats not enough to determine how much of a global threat the virus, dubbed 2019-nCoV, really is.
What matters is the route of transmission, Mike Ryan, the WHOs director of health emergencies, told reporters Wednesday. So far, Chinese health authorities have presented evidence that suggests the respiratory virus is spreading through close contact with infected individuals, as is typical with coronaviruses. If thats the only route, the outbreak is containable, Ryan said. But at this time it is not possible to determine that absolutely.
To better assess how the virus is traveling between people, the WHO is requesting more details from China about its rapidly growing number of cases. Specifically, the health agency would like to see data on when patients started showing symptoms, so it can start calculating how quickly the virus is moving through the population. WHO officials also want to know how Chinese health authorities are tracking potential exposures.
In addition, the agency has encouraged countries that have experienced exported cases to share any information they have about possible spread. So far, WHO officials have seen no evidence of the virus spreading within other countries, though that may change. The independent panel will reconvene Thursday, at which point it intends to make a recommendation to the WHO on whether the outbreak amounts to an international emergency. A declaration by WHO would give the agencys guidelines for how to combat the outbreak the power of international law, spurring action and funding from governments around the globe.
Another key question the group will weigh is just how deadly the coronavirus is. Compared to SARS and MERS, 2019-nCoV appears to have a much lower fatality rate, so far mostly killing elderly people with underlying health issues. According to data shared by the Chinese National Health Commission, 72 percent of all cases in China have occurred in people over the age of 40. But this is one of the aspects for which wed like to have more information, said Didier Houssin, chair of the emergency committee.
While the public health experts debated and deliberated, Chinese officials took more drastic action, moving to shut down the 11-million person city of Wuhan, which has been at the center of the outbreak. The state-owned Peoples Daily newspaper said in a tweet that no one would be allowed to leave the city starting at 10am local time Thursday.