Health authorities’ concern about the new coronavirus in China, with cases spreading in Asia and as far as the United States, deepened Wednesday with news that the Chinese government plans to shut down transportation from Wuhan, a city of 11 million people that is considered ground zero of the pneumonia-like virus.

After the outbreak began in December, the Chinese government for weeks portrayed it as a problem largely restricted to Wuhan, in the Hubei province. Infections have since been found in the Chinese territories of Hong Kong and Macao, and in South Korea, Japan, Taiwan — as well as in this country in Washington state. Of particular concern: The news Monday that Chinese authorities had determined that the virus can be spread by human-to-human contact, and that 14 health-care workers had been infected by a single carrier. As of Wednesday, 17 people have died and more than 470 have fallen ill with the virus, The Post reported.

China’s seeming reluctance to share information in the early stages of the outbreak slowed the international recognition of the threat. A turning point came when video footage surfaced earlier this month showing Chinese health authorities — clad in full-body protective suits — examining passengers on an airplane. The earlier secrecy raises doubts that China has fully learned key public health lessons since the SARS virus killed nearly 800 people in 2003 and then MERS claimed some 850 lives a decade later.

This time, the world is better prepared to deal with the threat. Though the warning signs are unsettling, there is reason to believe that the virus may mostly cause mild illness and can be contained without major impacts. But how it unfolds will turn on some critical questions and on actions that still need to be taken.

As with the MERS and SARS viruses, the Wuhan pneumonia is caused by a novel coronavirus that jumped from animals to people. Poor animal husbandry in open food markets make China an epicenter for these risks. Wuhan’s bazaar sells freshly slaughtered animals — including chickens, pheasants, marmots, snakes, deer and rabbits. These “wet markets” create perfect conditions for viral species to spread from their animal hosts to humans.

Coronavirus is a species implicated in bad colds and, on rare occasion, viral pneumonia. Seven strains are already known to circulate among humans. The bug behind the Wuhan outbreak is new, which makes its emergence a cause for significant concern. Humans may not have much immunity to its main components.

By some measures, Chinese health authorities have put us ahead in addressing the risks. Unlike SARS, which took about five months to firmly identify after it first began to spread, the Wuhan virus has been quickly sequenced and large-scale containment efforts were implemented early. China has already made diagnostic tests available to its health-care system.

Yet, on other measures, more-seamless information-sharing by Chinese authorities is needed. They published the sequence of the viruses they had isolated, but China doesn’t appear to have shared viral samples with key international health authorities who could have used the pathogen to help validate diagnostic screening tests and evaluate potential antidotes.

It is now up to other countries to work together on steps to avert wider outbreaks or pandemic spread.

First, we need to better understand the nature of this bug, and its severity. The illness may be more widespread than we realize in the fog of viral war. Because its incubation period is likely to be as much as a week, travelers can be harboring the infection and show no symptoms. A key to containing the virus’s wider spread will be developing effective point-of-care diagnostics to implement more widespread screening of patients.

We learned that lesson with the mosquito-borne Zika virus when it was first reported in the United States in 2015. Initially, most blood samples had to be shipped to a central lab operated by the Centers for Disease Control and Prevention. That slowed diagnosis and limited the ability of doctors to intervene more quickly when patients were infected. Health-care providers urgently need easy access to effective diagnostic tests for the Wuhan virus.

There’s much we don’t know yet, but answers should emerge that will help us gauge the risks. It’s troubling that the virus seems to have jumped quickly from animal to human transmission. But, for most people, it might cause only a mild illness. For the young, old or infirm, an infection could be more serious.

Yet even if it the Wuhan virus doesn’t mutate into a more potent illness, as it could, it’s a disturbing reminder that we remain too vulnerable to these zoonotic threats, as illnesses that spread from animals to humans are known. One day, a virus will occupy the terrifying spot where lethality and dissemination meet. It will be nimble enough to propagate widely and virulent enough to cause catastrophic harm. The Wuhan episode shows that while we’ve learned some lessons from SARS and MERS, we remain tragically vulnerable.

Read more:

Ronald A. Klain: The coronavirus has landed in the U.S. Here’s how we can reduce the risk.

Leana Wen: Governments need people’s trust to stop an outbreak. Where does that leave us?

The Post’s View: China should embrace the lessons of previous outbreaks to combat the new coronavirus

Anna Fifield: As families tell of pneumonia-like deaths in Wuhan, some wonder if China virus count is too low

What is coronavirus and how does it spread? Coronaviruses are a large family of viruses whose effects range from causing the common cold to triggering much-more serious diseases, such as severe acute respiratory syndrome, or SARS, which can affect humans and animals, according to the World Health Organization. China has confirmed that the new strain is being transmitted between humans. Here’s what we know so far about the virus.

Mapping the spread of the new coronavirus: The United States, Thailand, Japan, Taiwan and South Korea have all confirmed cases of the infection, which emerged last month in east-central China.

Wuhan, the Chinese city of 11 million people where the coronavirus outbreak began last month, has taken the unprecedented action of suspending all outbound travel beginning at 10 a.m. Thursday.

First case in the U.S. is confirmed: A man in Washington state was diagnosed with the virus after returning from the Wuhan region in mid-January. His condition is stable but is being monitored as a cautionary measure, officials said.

U.S. Health officials are screening travelers from Wuhan arriving at the international airports in Los Angeles and San Francisco and at New York’s John F. Kennedy International Airport. They will soon be screening travelers arriving from Wuhan at Chicago’s O’Hare and Atlanta’s Hartsfield-Jackso n international airports. And in the coming days, all flights from Wuhan to the United States will be redirected so their passengers’ point of entry is one of those five airports.

Scott Gottlieb, a resident fellow at the American Enterprise Institute, was commissioner of the Food and Drug Administration from May 2017 to April 2019. He consults for and invests in biopharmaceutical companies.