Pien Huang

This story was updated on June 1 to include WHO's reaction from its daily press conference.

Tedros Adhanom Ghebreyesus, director-general of the World Health Organization, said he learned of President Trump's intentions of "terminating" the decades-long U.S. relationship with WHO through Trump's press briefing on Friday.

As the world seeks to join together to bring the novel coronavirus under control, President Trump has sent a letter to the World Health Organization threatening that the U.S. will halt all funding and consider leaving the agency, pending an assessment of its response to COVID-19.

The U.S. has the most coronavirus deaths of any country in the world — on May 11, the death toll passed 80,000.

And that's likely an undercount.

This week, the question of mutation has been front and center in coverage of the coronavirus — from controversial claims about changes that make the virus more contagious to reassurances that any mutations are not yet consequential.

Here are some of the questions being raised — and what the specialists can (and can't yet) say to answer them.

Is the coronavirus mutating?

Updated on May 19 at 8:51 a.m. ET

The World Health Organization describes its job as "the global guardian of health."

It is now possibly facing the most devastating global health threat in its 72-year history: the coronavirus pandemic. WHO is devoting hundreds of millions of dollars and an all-hands-on-deck approach to the effort to vanquish the virus.

And it is being accused of failing to uphold its mission.

The fight against coronavirus will not be won until every country in the world can control the disease. But not every country has the same ability to protect people.

President Trump's plan to put a hold on U.S. funding for the World Health Organization during a global pandemic "is as dangerous as it sounds," says billionaire philanthropist Bill Gates. The Microsoft founder joined others defending the WHO, which they say is doing vital work to fight COVID-19.

The coronavirus has plunged the world into a crisis that's being compared to World War II and the Great Depression. It's the worst time possible, Gates and others say, to take money away from the U.N. health agency.

Coronavirus case counts are rising exponentially in Africa. Since the continent saw its first case, in Egypt in mid-February, some 10,000 cases and 500 deaths have been confirmed.

As the new coronavirus continues to spread around the globe, researchers say the virus is changing its genetic makeup slightly. But does that mean it is becoming more dangerous to humans? And what would the impact be on any future vaccines?

The fact that the novel coronavirus appeared in the middle of flu season has prompted inevitable comparisons. Is COVID-19, the disease caused by the virus, pretty much similar to the flu or does it pose a far greater threat?

Although there are still many unknowns about COVID-19, there is some solid information from researchers that sheds light on some of the similarities and differences at this time.

Symptoms

On Weibo, the Chinese version of Twitter, user 一只猫叫鱼Yu kept a public diary of her lockdown experience in Wuhan, China. On day 29, she described losing track of time. "I watch the days go by one after another," she wrote. "I don't know how long days like this are going to last."

Updated on March 17 at 5:06 p.m. ET

Mild.

Moderate.

Serious.

Severe or extreme.

These are some of the adjectives being used to describe the symptoms displayed by patients with COVID-19. Vice President Pence used them in his remarks to the nation last week:

"Some — some large percentage have mild flu symptoms; some have serious flu symptoms."

Keep your distance. And don't kiss.

Those are two pieces of advice that could be crucial in reducing the spread of the coronavirus.

Public health officials say the spread has been mainly driven through people spending time indoors with others who have the disease.

"Looks like the main driver is not widespread community infection — looks like it's household-level infection," Dr. Bruce Aylward, a senior adviser to the World Health Organization, said at a news conference in Geneva on Feb. 25.

Updated Feb. 21, 11:46 a.m. ET

Last month, a British man went to a conference in Singapore, then on a ski trip to the French Alps.

What he didn't know when he arrived in the Alps was that he was infected with the virus behind the COVID-19 outbreak.

During his stay at a ski village, it appears he infected 11 other people, who subsequently traveled on to the U.K. and Spain, the World Health Organization says.

Updated on March 6 at 3:45 p.m.

It's the season for colds and flus — and a newly identified respiratory disease, COVID-19.

To cut your risk of catching a respiratory illness on your next flight, experts offer two pieces of common-sense advice: Wash your hands frequently and keep a distance from people who are sick.

Where to sit to prevent getting sick

A 2018 study suggests that to minimize contact with other passengers, you should pick a window seat and stay put.

Like Ebola virus in Africa and the Nipah virus in Asia, the new coronavirus — 2019-nCoV — appears to have originated in bats.

Chinese researchers took samples of the coronavirus from patients in Wuhan, the city in central China where the outbreak was first detected.

They compared the genetic sequence of the new coronavirus — 2019-nCoV — to a library of known viruses and found a 96% match with a coronavirus found in horseshoe bats in southwest China. The findings were published in a study in Nature this week.

Updated at 12:26 p.m. ET

Saturday's Lunar New Year celebrations were dampened in China by fears over the coronavirus outbreak and travel restrictions affecting 46 million people.

On the first day of the Lunar New Year, China's President Xi Jinping stressed the urgency of controlling the outbreak — which has seen hundreds more confirmed cases since Friday — and urged state authorities to prioritize containment efforts.

"I don't feel in the Chinese New Year mood at all this year," a netizen with username 朱一龙qwertyuiop416 posted this week on Weibo, China's equivalent to Twitter. "I'm panicking. I'm getting more scared every day."

That sentiment reflects a trend on Chinese social media as confirmed cases of the Wuhan coronavirus surge.

Initially, there was some lightheartedness in posts. One Weibo user commented it was "the perfect time" to stay home and play a mobile phone game called Plague Inc.