Sen. Amy Klobuchar (D-Minn.), Sen. Bernie Sanders (I-Vt.), and former South Bend, Indiana, Mayor Pete Buttigieg participated in CNN town halls in Nevada on Tuesday night, days before the state's caucuses.

Sanders is leading in the polls and did well in Iowa and New Hampshire, but when asked if he is the Democratic frontrunner, Sanders responded, "Who cares?" He also questioned whether his supporters were really sending threatening messages to Culinary Union in Nevada leaders over the union's criticism of Sanders' heath-care proposals. "The idea that anybody who works with me would make a vicious attack against a union leader just because we disagree on an issue is incomprehensible to me," he said. "And you know what, I'm just not sure that that's true."

Buttigieg called out several people close to Trump, including Attorney General William Barr. Barr's politicization of the Justice Department is "an emergency of legitimacy in our justice system," he said. "Our justice system only works if it is immune from the interference of politicians."

He also scoffed at Trump ally Rush Limbaugh lecturing him on family values. Buttigieg said his marriage "never involved me having to send hush money to a porn star after cheating on my spouse," a reference to Trump's 2016 hush-money payoff, via his incarcerated former lawyer Michael Cohen, to porn actress Stormy Daniels.

Klobuchar said while it would be "cool" to be the first woman president, "I think the story that we tell and the campaign that we run has to be more than about that. It has to be about people's dreams." She also shared why she was unable to remember the president of Mexico's name last week when asked during an interview — an error Buttigieg brought up. "When that happened, for what it's worth, I had been in the Senate all day," Klobuchar said. "We had six votes, including a resolution to be a check on the president. And I got on a plane and got there at midnight my time and had a fast interview and two forums after that, I think ending at about two or three in the morning. Such is life." Catherine Garcia

Public health experts and government officials agree that the U.S. government's coronavirus death toll almost certainly understates how many Americans have actually died from the virus.

The Centers for Disease Control and Prevention only counts deaths where the presence of the coronavirus is confirmed in a lab test, The Washington Post reports, and "we know that it is an underestimation," CDC spokeswoman Kristen Nordlund said.

There are many reasons why the numbers are underreported. Strict criteria in the beginning of the outbreak kept many people from getting tested for coronavirus, and it's still difficult to get tested in some areas, for example. There's also the matter of false positives, and not all medical examiners have tests or believe they should conduct postmortem testing, even on people who died at home or in nursing homes where there were outbreaks. Experts also believe some February and early March deaths that were attributed to influenza or pneumonia were likely due to coronavirus.

The official death count is based on reports sent by states, and as of Sunday night, the CDC reports 304,826 confirmed U.S. cases and 7,616 deaths. The Post, other media outlets, and university researchers update their numbers more frequently, with the Post reporting on Sunday night that 9,633 people have died from coronavirus in the U.S., and at least 337,000 cases have been confirmed. Catherine Garcia

A fight broke out in the White House Situation Room on Saturday, after President Trump's economic adviser Peter Navarro clashed with Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, over an unproven COVID-19 coronavirus treatment, Axios reports.

Four people with knowledge of the matter told Axios' Jonathan Swan the argument took place near the end of a White House coronavirus task force meeting, after Food and Drug Administration Commissioner Stephen Hahn brought up hydroxychloroquine, an antimalarial drug Trump has touted as a possible "game-changer" in the fight against coronavirus. When Hahn was finished giving updates on drug trials, Navarro put folders down on the table where Hahn, Fauci, Vice President Mike Pence, and others were sitting.

One person familiar with the conversation told Swan the "first words out of his mouth are that the studies that he's seen, I believe they're mostly overseas, show 'clear therapeutic efficacy.' Those are the exact words out of his mouth." Fauci responded that this was anecdotal evidence, and this "just set Peter off," Swan reports. Navarro pointed to the folders and said, "That's science, not anecdote," a source said, and as his voice continued to get louder, Pence tried to intervene. "It was pretty clear that everyone was just trying to get Peter to sit down and stop being so confrontational," another person told Swan.

Fauci and other public health officials have said more data is needed before anyone can say the drug is effective against COVID-19, but based on things he's read, Navarro is convinced it works, Swan reports. The task force ultimately decided that publicly, the White House needs to say that use of hydroxychloroquine is between doctors and patients. Read more at Axios. Catherine Garcia

Queen Elizabeth II delivered a rare televised address on Sunday, calling on the British people to keep doing their part to stop the spread of the COVID-19 coronavirus, reminding them that "while we may have more still to endure, better days will return."

On Sunday, the death toll from COVID-19 hit 4,934 in Britain. The queen declared that "together we are tackling this disease, and I want to reassure you that if we remain united and resolute, then we will overcome it. While we have faced challenges before, this one is different. This time we join with all nations across the globe in a common endeavor, using the great advances of science and our instinctive compassion to heal. We will succeed, and that success will belong to every one of us."

Queen Elizabeth thanked health care workers for their tireless efforts to save lives, as well as everyone staying at home, and said she was reminded of the 1940 address she made with her late sister Margaret. They spoke to children who were evacuated during the German bombing raids in World War II, and "today, once again, many will feel a painful sense of separation from their loved ones," she said. "But now, as then, we know, deep down, that it is the right thing to do."

The 93-year-old queen and her 98-year-old husband, Prince Philip, are at Windsor Castle. Their 71-year-old son Prince Charles tested positive for the COVID-19 coronavirus and has recovered. The queen's address was recorded in a large room, where the only other person was the cameraman, Reuters reports; he wore gloves and a mask. The queen delivers a Christmas message every year, but otherwise has only made a handful of televised addresses during her 68-year reign. Catherine Garcia

Nadia, a 4-year-old Malayan tiger at the Bronx Zoo in New York, has tested positive for the COVID-19 coronavirus.

She is the first of her kind to test positive for the virus, CNN reports. In a statement, the Bronx Zoo on Sunday said Nadia, her sister Azul, two Amur tigers, and three African lions recently developed dry coughs, but no other animals are showing symptoms of COVID-19. Nadia was tested "out of an abundance of caution," and the zoo said it "will ensure any knowledge we gain about COVID-19 will contribute to the world's continuing understanding of this novel coronavirus."

The cats have all "experienced some decrease in appetite," but otherwise are "doing well under veterinary care and are bright, alert, and interactive with their keepers." All are expected to make full recoveries. The zoo also said the cats were "infected by a person caring for them who was asymptomatically infected with the virus or before that person developed symptoms," and there are now "appropriate preventative measures" in place for staffers taking care of the animals. Catherine Garcia

U.S. Surgeon General Jerome Adams on Sunday called the next week of the novel COVID-19 coronavirus pandemic the modern era's "Pearl Harbor moment." In other words, it'll be the "hardest moment" of many Americans' lives, and Adams hopes every person in every state does their part to slow the spread.

But while Washington Gov. Jay Inslee (D) may agree with most of that assessment, he told NBC's Chuck Todd during Sunday's edition of Meet The Press that he isn't sure why the federal government is so intent on remaining as a backup for the states, especially if the White House believes we're in a war-like moment.

"We need a national mobilization of the manufacturing base of the United States as we started on Dec. 8, 1941," Inslee said, calling on President Trump to authorize the Defense Production Act. Tim O'Donnell

Former Food and Drug Administration Commissioner Scott Gottlieb has issued some dire warnings since the early days of the novel COVID-19 coronavirus, but on Sunday he indicated some steps taken by the U.S. federal government and states might be paying off — both in terms of curbing the spread and preparing the health-care system for an onslaught of patients.

New York City remains the epicenter of the U.S. outbreak, and its hospitals are struggling. Gottlieb reiterated the predication made by numerous officials that the city, and New York state, are on the verge of peaking next week, which will undoubtedly stretch the health-care system thin. But he said he, ultimately, he thinks there will be enough ventilators for severe COVID-19 patients thanks to a historic effort to expand their supply, preventing New York from going past its tipping point.

As for the rest of the country, Gottlieb believes mitigation efforts like social distancing are "clearly working," as case rates slow in northern states, though he's concerned the next set of hot spots will be in the South. Tim O'Donnell