Pien Huang

The U.S. has sent a letter officially notifying the United Nations that it is leaving the World Health Organization, starting the formal process of withdrawal that President Trump first threatened in April when he halted funding to WHO.

The world is being flooded with new terms in coverage of the COVID-19 global pandemic. Here's a glossary in case you're not up on the latest medical and testing jargon. We start with the nomenclature of the virus. Words are listed in thematic groupings (transmission and testing, for example).

Minks on two fur farms in the Netherlands began getting sick in late April. Some were coughing, with runny noses; others had signs of severe respiratory disease. Soon, they started dying.

Researchers took swabs from the animals and dissected the ones that had died.

The culprit: SARS-COV-2, the novel coronavirus causing a global pandemic.

Even if someone is infected by the novel coronavirus and remains asymptomatic — free of coughing, fever, fatigue and other common signs of infection, that doesn't mean the coronavirus isn't taking a toll. The virus can still be causing mild — although likely reversible — harm to their lungs.

In the midst of the coronavirus pandemic, the World Health Organization took time at its daily press conference to address another pressing issue: the wave of protests against police violence and racial injustice. The demonstrations began in the U.S. when George Floyd died on May 25 after a police officer had pressed a knee into his neck for 8 minutes and 46 seconds while detaining him in Minneapolis.

The protests are now spreading around the world to Europe, Africa and other regions.

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."