"It is hard for many people to intuitively appreciate exponential growth," Yale science professor and physician Nicholas Christakis tweeted Wednesday. "Nothing seems to be happening for a long time, until a lot happens at once." A lot happened on Wednesday night.

In short order, President Trump gave an Oval Office address, since clarified, that included a partial ban on travel to and from Europe, the NBA indefinitely suspended its season, Tom Hanks announced that he and his wife have tested positive for the COVID-19 coronavirus, and Sen. Maria Cantwelll's (D-Wash.) office said one of its staffers has also tested positive, putting the new virus inside the U.S. Capitol.

But right before any of that happened, former Alaska Gov. Sarah Palin was unmasked as the bear on The Masked Singer, and she rapped the Sir Mix-A-Lot hit "Baby Got Back."

Maybe that should have been a sign.

"When something dangerous is growing exponentially, everything looks fine until it doesn’t," Megan McArdle writes in The Washington Post. "The crisis in northern Italy is what happens when a fast doubling rate meets a 'threshold effect,' where the character of an event can massively change once its size hits a certain threshold. In this case, the threshold is things such as ICU beds. If the epidemic is small enough, doctors can provide respiratory support to the significant fraction of patients who develop complications, and relatively few will die. But once the number of critical patients exceeds the number of ventilators and ICU beds and other critical-care facilities, mortality rates spike."

In any case, you can watched Palin's masked performance below. Peter Weber

As the search for a coronavirus vaccine continues, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, is feeling "cautiously" optimistic.

"Given that the body can make a good response against coronavirus, we feel cautiously optimistic that if we mimic safely natural infection with our vaccine, we will be able to induce a response in a person that would be equivalent to the response that natural infection induces," Fauci explained on Tuesday, The Wall Street Journal reports.

Fauci, a member of President Trump's coronavirus task force, was optimistic that several COVID-19 vaccine candidates will be shown as effective in "a reasonable period of time" and pointed to the promising early data from Moderna, per the Journal, though he added that a major unanswered question is for how long any eventual vaccine might provide protection from the coronavirus.

"What is a big unknown is what the durability of that protection is," he said. "Is it going to be a year, two years or even maybe, unfortunately, six months or less?" If it provides protection for a fairly short period, he said this might lead to a "secondary problem" in trying to get enough doses out.

Speaking to the Journal of the American Medical Association, Fauci on Tuesday reiterated he's "cautiously optimistic" about getting a vaccine and pointed to the administration's hope of having a few hundred million doses available by the beginning of 2021, per CNN, though some experts have cast doubt on this incredibly tight timeline. But while he's feeling hopeful about the progress, Fauci also noted this week that there's "never a guarantee, ever, that you're going to get an effective vaccine." Brendan Morrow

A review of 172 studies on coronavirus transmission from 16 countries confirmed that wearing a face mask and maintaining physical distance significantly reduced the risk of spreading COVID-19. The first-of-its-kind study, funded by the World Health Organization and published Monday in the journal The Lancet, also attempted to quantify how much each measure cut transmission risks by itself.

The risk of transmitting the new coronavirus without a mask or respirator is 17.4 percent, but with a mask that falls to 3.1 percent, the study found, though the researchers noted there's a higher amount of uncertainty on mask wearing than physical distancing. Keeping a distance of less than 1 meter (3.3 feet) and no other protective measure carried a transmission risk of 12.8 percent, cut to 2.6 percent when the distance was more than 1 meter and even lower at 2 meters (6.6. feet). There was also a sharp cut in risk with eye protection.

"In all three questions, the evidence appears to support the measures," Oxford University's Trish Greenhalgh, who wasn't involved in the study, tells CNN. "For example, on average, staying 1 meter away from other people appears to reduce your chance of catching COVID-19 by 80 percent. Wearing a mask or face covering appears to reduce your risk by up to 85 percent. And wearing goggles or a face shield seems to reduce it by up to 78 percent."

Still, the main takeaway is that "no single intervention on its own made an individual completely impervious to transmission," Dr. Derek Chu at Canada's McMaster University, who co-authored the study, told NBC Today. All three together seriously cuts the odds, and "we can't neglect basic measures such as hand hygiene." Peter Weber

Lea Michele has issued an apology after a Glee co-star called her out for alleged "traumatic microaggressions."

The actress in an Instagram post on Wednesday morning said she has been examining how "my own behavior towards fellow cast members was perceived by them" after on Monday, Glee's Samantha Ware claimed Michele made her "first television gig a living hell" with "traumatic" microaggressions on set and even told people that "if you had the opportunity you would 's--t in my wig.'"

"While I don't remember ever making this specific statement and I have never judged others by their background or color of their skin, that's not really the point, what matters is that I clearly acted in ways which hurt other people," Michele wrote. "Whether it was my privileged position and perspective that caused me to be perceived as insensitive or inappropriate at times or whether it was just my immaturity and me just being unnecessarily difficult, I apologize for my behavior and for any pain which I have caused."

Other black Glee stars had backed Ware up after she posted her claims, with Dabier Snell alleging Michele said he "didn't belong" at a table with the cast. Michele in her apology said she has "listened to these criticisms and I am learning and while I am very sorry, I will be better in the future from this experience."

Michele's apology came after HelloFresh ended a partnership with her as a result of the controversy, with the company saying it's "disheartened and disappointed" over the allegations. Brendan Morrow

Many faith leaders, including the Episcopal bishop and Catholic archbishop of Washington, forcefully denounced President Trump's iconoclastic usage of the Bible and Christian shrines for photo ops as he sent the U.S. military into the streets of the capital and ordered peaceful protests violently dispersed. The response from evangelical leaders was mixed, but the ones most closely aligned with Trump were delighted.

"Every believer I talked to certainly appreciates what the president did and the message he was sending," Robert Jeffress, the pastor of First Baptist Dallas and a avid Trump supporter, told The New York Times. He gleefully told The Atlantic's McKay Coppins "it was completely appropriate for the president to stand in front of that church" and "by holding up the Bible, he was showing us that it teaches that, yes, God hates racism, it's despicable — but God also hates lawlessness."

Ralph Reed, chairman of the Faith and Freedom Coalition, told Coppins that Trump's "presence sent the twin message that our streets and cities do not belong to rioters and domestic terrorists, and that the ultimate answer to what ails our country can be found in the repentance, redemption, and forgiveness of the Christian faith." Rev. Franklin Graham told The Washington Post he "was glad to see him stand in front of that church and hold up the word of God."

Samuel Rodriguez, an evangelical leader who has been advising Trump, said he, too, was glad to see the president hold up the closed Bible "like a boss," but added, "I hope peaceful protesters were not moved away with tear-gassing." And Pat Robertson, on the 700 Club, said now's the time for showing empathy and love, not military law and order or calling governors "jerks." "You just don't do that, Mr. President," he said. "It isn't cool."

"Trump doesn't quote anything from the Bible, he really just uses it as a pure symbol of partisan identity," Katherine Stewart, an expert on the religious right at the American Enterprise Institute, told the Times. "Authoritarianism frequently comes veiled in religion." Clemson University sociologists told The Atlantic the kind of Christian nationalism that drives Trump's evangelical base isn't about theology, "it's about identity, enforcing hierarchy, and order." Peter Weber

About 60 million Americans were under curfew in 200 cities on Tuesday night, the eighth day of protests sparked by the police killing of George Floyd. Thousands turned out in Washington, D.C, and hundreds stayed out after the 7 a.m. curfew, which federal and military police spread throughout the capital did not enforce, The Washington Post reports. Many showed up for the first time in response to Monday night's crackdown.

In New York City, thousands remained out after the 8 p.m. curfew, but throughout the U.S. things appeared to be calmer than on previous nights. Journalists are exempt from New York City's curfew, but New York Police officers surrounded two Associated Press reporters just after 8 p.m Tuesday night and shoved and screamed profanities at them until they left. Videojournalist Robert Bumsted, documenting the protests in lower Manhattan with photographer Maye-E Wong, captured some of it on video.

Both journalists were wearing AP identification and told police they were media, and Bumsted reminded one officer screaming at him that journalists are "essential workers" who are legally allowed to be out after curfew. "I don't give a s--t," one officer said. "Essential to who?" another yelled. "Who are you essential to? Who are you essential to?! Get back!" Still another cop tells Bumsted to "get the f--- out of here you piece of s--t." They separated Wong and Bumsted and only allowed them to reunite when Bumsted said Wong had the keys to his car.

NYPD officials told AP the department would "review this as soon as possible." AP spokeswoman Lauren Easton said journalists "report the news on behalf the public" and "it is unacceptable and deeply troubling when journalists are harassed simply for doing their job." Police in other cities have shot reporters with pepper balls and rubber bullets, gassed them, arrested them, and otherwise harassed them for no evident reason. Peter Weber

"For a week, America's streets have been filled with protesters enraged over the murder of George Floyd by police," Stephen Colbert said on Tuesday's Late Show, and Monday evening President Trump "finally appeared in the Rose Garden to calm a troubled nation — by threatening martial law." Responding to protests about police brutality by "threatening to send in the Army to crush them," he said, is "like forgetting your child's birthday and apologizing by sending in the Army to crush them."

Trump wanted to end his speech with a stroll to St. John's Church, Colbert said, but "there was a crowd of peaceful protesters in the way. So he had military police open fire with rubber bullets, flash grenades, and tear gas," and "once the path was cleared for Caesar's brave shamble, Trump made his way across the street to the boarded-up church, where he, with visible confusion and discomfort, groped a Bible" for the cameras.

Tooning Out the News had God deal with Trump's photo op.

Trump has always been "an armchair thug who glorifies violence," but his Rose Garden speech and its aftermath "was one of the most menacing moments" of his presidency, Late Night's Seth Meyers said. We're at the "worst-case scenario where our democracy crumbles and our country descends into authoritarianism," he added. "There's no on-off switch. Democracy, it turns out, is on a dimmer."

Yes, "our president, if we can still even call him that, seems to believe he is the warden overseeing a prison break," Jimmy Kimmel said. "This is a week that any other president would have gone on TV and at least tried to bring us together," but Trump "can't even go through the motions."

"Mr. Tough Guy was whisked into a panic bunker on Friday as crowds assembled outside the White House — it took three-and-a-half years, he finally got that massive crowd to show up for him in D.C.," Kimmel joked wryly. "And the reports that he was holed up and hiding must have really gotten under that orange skin," because he had Attorney General William Barr gas protesters so he could go outside and hold "a Bible upside-down in front of a church." He ended by trying to explain white privilege for people who, like him, were skeptical: "White privilege doesn't mean your life hasn't been hard, it just means the color of your skin isn't one of the things that makes it harder." Watch below. Peter Weber