President Trump's physician Dr. Sean Conley was evasive when asked multiple times on Monday about the last time Trump tested negative for the coronavirus before his diagnosis last week.

Conley addressed reporters Monday afternoon outside Walter Reed hospital, where Trump has been receiving treatment for COVID-19, a few hours before the president's scheduled discharge. The question about Trump's testing history was asked repeatedly, but Conley dodged, offering no detail and simply saying, "I don't want to go backwards."

Reporters were searching for the answer because it's still unclear when and where Trump first contracted the virus, as well as who else may have been exposed in light of a growing list of positive tests connected to the White House. Conley did say contact tracing was underway, but that doesn't fall under his jurisdiction. Tim O'Donnell

Moderna announced Tuesday it has started dosing the first participants in a study of its COVID-19 vaccine in young children.

The company is studying its coronavirus vaccine in children between the ages of 6 months and 11 years old, and it said Tuesday that the first participants in this phase 2/3 study have been dosed, per The Wall Street Journal.

Moderna is expecting to enroll 6,750 healthy participants under 12 years old in the United States and Canada for the study, which is being conducted in collaboration with the National Institute of Allergy and Infectious Diseases and the Biomedical Advanced Research and Development Authority.

The COVID-19 vaccine from Moderna is one of three that has earned emergency FDA approval for adults in the United States. But Moderna CEO Stéphane Bancel said this study will "help us assess the potential safety and immunogenicity of our COVID-19 vaccine candidate in this important younger age population." Moderna previously launched a clinical trial to study its vaccine in children between 12 and 17 years old, Axios notes.

Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, predicted last month that there should be enough data "to be able to say that elementary school children will be able to be vaccinated" by "at the earliest, the end of the year, and very likely, the first quarter of 2022." Fauci also predicted that kids in high school should be able to get vaccinated "sometime this fall," "pretty close to" the first day of school. Brendan Morrow

A significant number of the 30 million Americans infected with COVID-19 have lingering symptoms months after their initial illness. And many of these people with "long COVID," or COVID long-haulers, are reporting that their symptoms improved or cleared up after getting vaccinated. "That's not how vaccines work, normally," Tom Avril writes in The Philadelphia Inquirer. "The idea is to prevent disease, not treat it."

There were concerns that getting vaccinated would actually exacerbate long-haulers' symptoms, including fatigue, brain fog, shortness of breath, headaches, insomnia, and inability to smell. But "it's clear that vaccines have helped some people with long COVID with their symptoms," Yale immunologist Akiko Iwasaki wrote in a recent Medium post, laying out three possible explanations for how vaccines attack long COVID. The evidence for these improvements has been largely anecdotal or based on informal polls among long-hauler support groups.

But a new study by University of Bristol researchers, not yet published or peer-reviewed, found a statistically significant improvement among long COVID patients who got either the Pfizer or Oxford-AstraZeneca vaccine.

COVID long-haulers who got the vaccine experienced "no significant worsening in quality-of-life or mental wellbeing," the researchers wrote, and "when compared to matched unvaccinated participants from the same cohort, those who had receive a vaccine had a small overall improvement in long COVID symptoms."

It's possible the improvements for vaccinated long COVID patients could be due to the placebo effect, or the immune response sparked by the vaccine could wipe out lingering reservoirs of coronavirus, clean the body of "ghost" viral fragments, or distract the body from a harmful autoimmune response — all theories floated by Iwasaki and other immunologists and virologists.

Either way, immunologist Dr. Nancy Klimas tells ABC News, "my advice to long-haulers is to get the vaccine, not because of this, but because they should anyway, and if they get this as a bonus, I want to know." Peter Weber

Prince Philip is out of the hospital.

The 99-year-old Duke of Edinburgh and husband of Queen Elizabeth II left King Edward VII's Hospital in London on Tuesday, a month after he was hospitalized on Feb. 16, BBC News and The Associated Press report.

When Philip was first admitted, Buckingham Palace described this as a precautionary measure that was taken after he felt "unwell." The Duke of Edinburgh was ultimately treated for an infection, and he "underwent a successful procedure for a pre-existing heart condition" after being transferred to another hospital, according to Buckingham Palace. He then returned to King Edward VII's Hospital.

Philip has been hospitalized several times in recent years, including in 2011 for a blocked coronary artery. But according to BBC News, this was his longest hospital stay ever. When Philip was initially admitted last month, reports indicated that his condition was unrelated to COVID-19. He and the queen were previously vaccinated against COVID-19. Brendan Morrow

The Jesuits, a Catholic order of priests that counts Pope Francis among its members, have pledged to raise at least $100 million to atone for the order's ownership and sale of enslaved Black people in the early days of the American republic, The New York Times reported Monday. Historians and Catholic officials said it is one of the largest efforts by an institution to atone for participating in slavery.

The money will be paid out through a new foundation, the Descendants Truth and Reconciliation Foundation, created through three years of discussions between Jesuit leaders and a group representing the descendants of 272 slaves the order sold to a Louisiana plantation in 1838 to save Georgetown College, now Georgetown University, the first Catholic institution of higher learning in the U.S. The sale raised $115,000, or about $3.3 million in today's dollars. Genealogists at the Georgetown Memory Project have identified about 5,000 living descendants of people enslaved by the Jesuits.

The new foundation is headed by one of the descendants, Joseph Stewart, and its governing board includes representatives from Georgetown and other institutions with roots in slavery. The Jesuits have already contributed $15 million and plan to raise the other $85 million over the next five years. About half the annual budget will go toward grants for organizations engaging in racial reconciliation, a quarter will fund educational grants and scholarships for descendants, and some of the money will go directly toward supporting the needs of old and infirm descendants, the Times reports.

Stewart wrote the Jesuit leadership in Rome in May 2017, calling for negotiations over the newly resurfaced Georgetown slave sale. The Jesuit superior general, Rev. Arturo Sosa, wrote back a month later, urging Stewart's group and American Jesuits to talk and describing the order's slaveholding past as "a sin against God and a betrayal of the human dignity of your ancestors." In August 2017, Rev. Timothy Kesicki, president of the Jesuit Conference of Canada and the United States, flew to Michigan to meet with the Stewarts and lay the groundwork for the new foundation.

"This is an opportunity for Jesuits to begin a very serious process of truth and reconciliation," Fr. Kesicki said in a statement. "Our shameful history of Jesuit slaveholding in the United States has been taken off the dusty shelf, and it can never be put back." Peter Weber

The U.S. has administered more than 100 million COVID-19 shots, but "there still isn't anywhere near enough vaccine to go around," Jimmy Kimmel said on Monday's Kimmel Live, "and even when there is, the worry is that people will not want it — 49 percent of Republican men say they will not get the vaccine. Suddenly they're against baring their arms."

In fairness to Republicans, they're getting starkly mixed messages, Kimmel added. "The pandemic isn't a big deal, it will wash away, it's no worse than the flu; but it was created by China to destroy us. Which is it? Is Trump not getting the credit he deserves for manufacturing the vaccine, or this how Bill Gates controls our minds? No wonder they're hesitant." Dr. Anthony Fauci "strongly urged Donald Trump to tell his followers to get vaccinated," he deadpanned, "and he probably will, he generally does the right thing."

Tooning Out the News was similarly skeptical Trump would follow Fauci's suggestion.

"Yesterday on Fox News, Dr. Fauci urged former President Trump to speak up about the coronavirus vaccine," Jimmy Kimmel said at The Tonight Show. Not only will Trump not respond to a direct appeal, he said, but "honestly, asking Trump to give people medical advice makes me nervous because you know one day he's gonna say something crazy like Sour Patch Kids can cure asthma." Fallon made his own Trump PSA just to be safe.

"Nearly 30 percent of Americans, and half of all Republican men, say they do not intend to get one of the vaccines," Stephen Colbert said at The Late Show. "First of all, I call dibs on theirs. Second of all, why? Why, Republican men, why? Your guy's the one taking credit for the vaccine even existing. You're insulting him by not getting jabbed!" Fauci used flattery to try to get Trump to step up, he noted, "but to get everyone their shots, we need leadership from every part of the community, which is why thousands of clergy members from a cross-section of faiths — imams, rabbis, priests, and swamis — are trying to coax the hesitant to get vaccinated against COVID-19. Reminds me of the old joke: A priest, a rabbi, an imam, and a swami walk into a bar, and it's okay because they all got vaccinated."

If you want the vaccine and can't find any, Conan O'Brien had an iffy solution. Peter Weber

Right now, demand for COVID-19 vaccines is outstripping supply but that will change in the coming weeks. Then the challenge will be to persuade people hesitant to get the vaccine to roll up their sleeves. And several recent surveys show that while vaccine hesitancy is falling overall in the U.S., "opposition among Republicans remains stubbornly strong," The Associated Press reports.

In a new AP-NORC survey, 42 percent of Republicans say they probably or definitely won't get vaccinated, versus 17 percent of Democrats. A recent NPR/PBS NewsHour Marist poll found that 49 percent of Republican men and 47 percent of Donald Trump supporters said they would opt out if a vaccine was offered to them, versus 6 percent of Democratic men. A CBS News-YouGov survey released Sunday recorded 33 percent of Republicans saying they would not get a shot and another 20 percent undecided.

Dr. Anthony Fauci, the nation's top infectious disease expert, told Fox News Sunday "it would make all the difference in the world" if Trump urged his supporters to get vaccinated, and longtime GOP pollster Frank Luntz told The Washington Post last week he didn't "need a focus group to tell me that nothing would have a greater impact than a Donald Trump PSA." He held a focus group of Trump supporters on Saturday, and it turns out Trump's endorsement wouldn't really move the needle.

Luntz's focus group heard pro-vaccine pitches from House Minority Leader Kevin McCarthy (R-Calif.) and other congressional Republicans, former CDC director Dr. Thomas Frieden, and former Gov. Chris Christie (R). The House Republicans made no inroads, and the participants were turned off by the PSA featuring every former president but Trump. Many of them didn't trust Fauci. But Frieden's "five facts" persuaded many of them to swing toward vaccination. "We want to be educated, not indoctrinated," said Adam from New York.

The participants said they were particularly swayed by Frieden's statements about the tens of thousands of people already vaccinated, the two decades of work on coronavirus vaccines — not just a year — and the near-unanimous willingness of doctors to get inoculated. They said their doctor or spouse could also persuade them, but politics was poison. By the end of the session, all 19 participants said they were more willing to get vaccinated.

"These people represent 30 million Americans, and without these people, you're not getting herd immunity," Luntz told the Post. He and other groups are testing differing messaging nationwide. Peter Weber