Enough with the worrying, former Vice President Joe Biden's brain surgeon says.

As some voters murmur that the gaffe-prone Democratic presidential candidate's age is cause for extra concern this campaign cycle, Dr. Neal Kassell — the man who performed surgery on Biden three decades ago following two brain aneurysms — came out swinging for his former patient.

Kassell dismissed fears about the 76-year-old Biden's mental faculties, noting that he's "as sharp as he was 31 years ago" and assuring people that the hemorrhage and subsequent operations did not result in any brain damage. "I am going to vote for the candidate who I am absolutely certain has a brain that is functioning," Kassell told Politico. "And that narrows it down to exactly one."

Biden's physician, Dr. Kevin O'Connor, backed up Kassell. "Vice President Biden is in excellent physical condition," he said. "He is more than capable of handling the rigors of the campaign and the office for which he is running."

In fact, several experts told Politico that voters are placing too great an emphasis on the age of several candidates, particularly the five septuagenarians who are running, including Democratic candidates Biden and Sen. Elizabeth Warren (D-Mass.), 70, and Sen. Bernie Sanders (I-Vt.), 77, as well as 73-year-old President Trump and his lone Republican challenger, former Massachusetts Gov. Bill Weld, who is 74.

"They have prospects for survival that extend well beyond the four-year term of the office," said Dr. Jay Olshansky, who led an American Federation of Aging Research study last month that sought to determine how likely it is that a candidate would die while in office. "The bottom line is their chronological age does not matter at all." Read more at Politico. Tim O'Donnell

Experts are seeing shocking similarities between the coronavirus that has now spread beyond China and the SARS outbreak of 2003.

Like the infectious pneumonia that has killed at least 17 people, SARS was caused by a coronavirus that originated in China. But when one of the virologists who helped identify the SARS virus visited Wuhan, where this virus originated, he didn't see nearly enough being done to fight it. People were out at markets without masks, "preparing to ring in the New Year in peace and had no sense about the epidemic," Guan Yi of the University of Hong Kong's State Key Laboratory of Emerging Infectious Diseases told Caixin. Airports were hardly being disinfected, Guan continued, saying the local government hasn't "even been handing out quarantine guides to people who were leaving the city."

The city did disinfect the market where the virus has been traced to, but Guan criticized Wuhan for that, saying it hurts researchers' abilities to track down the virus's source. "I've never felt scared," Guan told Caixin. "This time I'm scared."

A case involving the coronavirus was identified in Washington state on Wednesday, and cases have also been identified in Thailand, Japan, South Korea, and Singapore. A total of 639 cases were confirmed in China. Kathryn Krawczyk

From movie to Broadway musical ... back into movie?

That's the journey Mean Girls is going on, as Tina Fey is working on a feature film adaptation of the Broadway musical Mean Girls that is itself based on the 2004 movie of the same name, according to The Hollywood Reporter. There's no word yet on who might direct the film set up at Paramount, but Fey will write it, as she wrote the 2004 version.

This new Mean Girls, Uproxx notes, will be added to the "very short list" of films based on musicals based on films that aren't musicals — other examples include Hairspray and Little Shop of Horrors. To make it even more confusing, the original Mean Girls was based partially on the self-help book Queen Bees and Wannabes, technically making this a movie based on a musical based on a movie based on a book.

In a statement, Fey said she's "very excited to bring Mean Girls back to the big screen," comparing it to "my Marvel Universe," while producer Lorne Michaels said it's been "a joy to work on Mean Girls and to watch it go from film, to musical, and now to musical film." Now, Mean Girls: The Movie: The Musical: The Movie: The Ride may be the natural next step. Brendan Morrow

Democrats are continuing to make their impeachment argument by citing President Trump's allies and officials, this time getting in a dig at Rudy Giuliani in the process.

Sylvia Garcia (D-Texas), one of the impeachment managers who spoke Thursday in Democrats' second day of opening arguments in the Senate's trial, took apart the conspiracy theory pushed by Trump that it was Ukraine, not Russia, that interfered in the 2016 election by hacking the Democratic National Committee.

To make her point that this theory has no basis in reality, Garcia referred to the words of Trump's former Homeland Security adviser, Tom Bossert, who told ABC News last year this "conspiracy theory" has been "completely debunked." Bossert in the clip played in the Senate went on to voice frustrations with Giuliani, Trump's personal lawyer, for pushing this conspiracy theory, quoting a former senator's magazine article as saying that one of the "ways to impeach oneself" is "hiring Rudy Giuliani."

Previously, Garcia played a clip of FBI Director Christopher Wray stating in an interview, "We have no information that indicates that Ukraine interfered with the 2016 presidential election." This was another example during Democrats' impeachment arguments of using clips from Trump allies and officials to make their argument after House Judiciary Chair Jerrold Nadler (D-N.Y.) made strategic use of 1990s-era quotes from Sen. Lindsey Graham (R-S.C.) and Alan Dershowitz, a member of Trump's impeachment defense team, to argue abuse of power is impeachable.

HuffPost's Ryan Reilly reports that when Bossert in the clip quipped that hiring Giuliani is a way to self-impeach, there were "a lot of laughs on both sides of the Senate chamber." Brendan Morrow

Fifth grade, meet the Senate floor.

During Wednesday arguments in President Trump's impeachment trial, senators seemed to have trouble staying awake and even staying in the room. So Sen. Richard Burr (R-N.C.) broke out a middle school solution, passing out fidget spinners to Republicans at the "Carolina Cookout" lunch he hosted Thursday, CQ Roll Call reports. USA Today's Nicholas Wu noticed a few of Burr's colleagues had taken him up on the offer.

Along with Burr, Sens. Rand Paul (R-Ky.) and Marsha Blackburn (R-Tenn.) found their own ways to pass the time, some more disengaging than others.

But none of the boredom-staving measures were enough to keep Sen. Lindsey Graham (R-S.C.) from walking out again. Kathryn Krawczyk

House Judiciary Chair Jerrold Nadler (D-N.Y.) is making his impeachment argument with a little blast from the past.

Nadler during Democrats' impeachment arguments on Thursday made use of 1990s-era clips of allies of President Trump, the first being Alan Dershowitz, who's serving on Trump's defense team. While arguing that abuse of power is an impeachable offense, Nadler pointed to Dershowitz — or "at least Dershowitz in 1998," he said.

In an old clip Democrats then played, Dershowitz says "you don't need a technical crime" to impeach a president if they are "somebody who completely corrupts the office of president, and who abuses trust, and who poses great danger to our liberty."

Later, Nadler turned to the words of one of his colleagues, Sen. Lindsey Graham (R-S.C.), who during the impeachment of former President Bill Clinton argued a crime isn't required to impeach a president. In an old clip, Graham says that "when you start using your office and you're acting in a way that hurts people, you committed a high crime."

Although Graham is in attendance for the impeachment trial, The New York Times' Catie Edmondson reports the Republican senator "left the Senate floor minutes before Nadler started playing the video of him." But The Daily Beast's Sam Brodey reports Nadler drew "some astonished looks" from Democrats when he played the Graham clip, including from Sen. Brian Schatz (D-Hawaii), who reportedly "shook his head and looked around at neighbors." Brendan Morrow

Behold, the impeachment contradiction of contradictions.

It's not surprising that a full 91 percent of Democrats have said they think President Trump "definitely" or "probably" did something illegal to warrant his impeachment, as a recent Pew Research Center poll found. But a solid 32 percent of Republicans or those who lean Republican have also said the same about Trump's conduct — not that they necessarily think it should warrant his removal.

Yes, of Republicans who are either "definitely" or "probably" convinced Trump's behavior was illegal, a full 59 percent say that doesn't mean he should be removed from office, Pew found. As for those Republicans who say Trump has "definitely" or "probably" done something unethical, 78 percent believe he should remain.

Pew surveyed 12,638 people from Jan. 6–19 via phone and online, with a 1.3 percent margin of error. Kathryn Krawczyk