When it comes to understanding how coronavirus spreads, most of us have heard about the R number – the average reproduction number of people infected by one other person. But Zeynep Tufekci says it’s more telling to look at a different letter: K. It’s the subject of her latest prescient article in The Atlantic, and she joins Christiane to explain.

British Prime Minister Boris Johnson is one of the few world leaders who truly understands what President Trump faces following his COVID-19 diagnosis. Earlier this year, Johnson was rushed to intensive care due to the virus. Mark Landler of the New York Times joins the program to compare Trump's diagnosis to Johnson's.

President Trump and the First Lady have tested positive for the coronavirus and are now experiencing “mild symptoms” according to the White House. At 74 years old and clinically obese, the president is a high risk patient. Former acting surgeon general Boris Lushniak joins Christiane to explain the medical risks and assess how this infection could have reached the commander in chief.

This diagnosis is the most serious known health threat to a sitting U.S. president in decades. President Trump’s team says he will continue his duties while recovering, but with 32 days to go before the election, how will this impact the campaign? And what are the constitutional norms for such a situation? Christiane speaks with journalist Ryan Lizza and constitutional scholar Deborah Pearlstein.

Too hot; jarring; exhausting. These are just some of the ways Republicans have described Tuesday’s debate, offering some rare pointed criticisms of their candidate. What does the Trump inner circle make of it? Media mogul Christopher Ruddy has known President Trump for two decades and joins the program to discuss.

Julián Castro was the only Latino candidate to run for president this election season. He previously served as mayor of San Antonio, Texas and was secretary for housing and urban development under President Obama. Though a strong critic of Biden’s record on immigration, Castro tells Walter Isaacson why he believes the former vice president is the man for the job.

Black History Month begins today in the UK. One person marking it in a unique way is Misan Harriman, who recently made history as the first Black male photographer to shoot the cover of British Vogue. The cover became a defining image of London’s Black Lives Matter protests, and now Harriman's auctioning it off for charity. He joins the show from the auction house Sotheby.

Gloria Steinem has spent a lifetime fighting for women’s rights, and now her story has been adapted into a biopic, "The Glorias." She joins the program to discuss the film and the current political scene, along with veteran director Julie Taymor.

America and the world tuned in last night for the presidential debate--the first between President Donald Trump and former Vice President Joe Biden. The debate became a study in chaos, mostly due to interruptions by President Trump. What did American voters think? To discuss, Christiane speaks with pollster Frank Luntz and Kevin Sheekey, Michael Bloomberg’s former campaign manager.

Today, former FBI Director James Comey testifies before the Senate Judiciary Committee over the FBI’s 2016 Russia investigation-- the latest twist for a man whose career was transformed by fractious relationships with both Hillary Clinton and Donald Trump. Now, the tale is dramatized in a new miniseries. Emmy Award-winning actor Jeff Daniels plays the title role. He speaks with Hari Sreenivasan.

While foreign policy was barely mentioned in Tuesday’s debate, one country did come up repeatedly: China. Each candidate accused the other of being soft on Beijing. Now, a new report from the House Intelligence Committee warns that Washington is ill-eqipped to counter a rising China. Committee chair Adam Schiff joins the program from D.C. to discuss.

Concerns are mounting over voter suppression, and President Trump has refused to commit to a peaceful transfer of power if he loses. A disputed election would likely be decided by the courts. But a host of supporting players, including state attorneys general, could become involved. Maura Healey occupies that office in Massachusetts and has vowed to battle any election interference.

Europe is currently battling a second wave of the coronavirus pandemic. France may have to lock down again, and Germans are facing new restrictions as their Chancellor, Angela Merkel, warns of a very difficult time ahead. To discuss all this, Christiane speaks with German lawmaker Norbert Röttgen and Gérard Araud, who previously served as French President Macron’s ambassador to the United States.

After a three-year study, the Commission on the Practice of Democratic Citizenship has published 31 recommendations to help America -- termed a "nation in crisis." The bipartisan commission of academic, civic, and political leaders includes Eric Liu and Pete Peterson. They join Michel Martin to discuss their findings and recommendations for a way forward.

The New York Times finds that -- according to the President's tax records -- Trump paid only $750 in federal income tax in his first year as president, and no income taxes at all for at least a decade before that. The report also points towards staggering debts and potential conflicts of interest that may directly threaten national security. To discuss this, Christiane speaks with H.R. McMaster.

A new study shows Black and Latinx Americans are twice as likely to test positive for COVID-19 as white people. Global Health expert George Aumoithe recently explored the pandemic's racial disparities in a Washington Post article titled “The racist history that explains why some communities don’t have enough ICU beds.” He speaks with Michel Martin about the history of healthcare policy in the U.S.

In a time of crisis, one of the most overlooked issues is the critical global collapse in biodiversity. Today 64 world leaders, preparing for a United Nations summit on the issue this week, pledged to reverse the decline by 2030. But is it a case of too little, too late? To answer that question, Christiane speaks with National Geographic Explorers Dereck and Beverly Joubert.

Paul Rusesabagina, who was awarded the Presidential Medal of Freedom after saving 1,200 people trapped in his hotel by machete-wielding marauders, was arrested and charged with terrorism earlier this month. To assess this reversal of fortune, Christiane speaks with journalist Anjan Sundaram, who has written extensively about Rwanda's increasingly authoritarian political climate.

The pandemic has thrown education into chaos, forcing students and teachers to adapt to new and often frustrating ways of learning. But Jaime Casap says the news is not all bad. He spent 15 years at Google working out ways to use technology in improving our learning experiences. The education evangelist speaks with Ana Cabrera about his discoveries.

After growing up in Iran and attending boarding school in the UK, Firooz Zahedi went from the diplomatic corps to art school to Andy Warhol’s "Interview" magazine. Along the way, he became Elizabeth Taylor’s close friend and favorite photographer, going on to capture images of Hollywood’s royalty. Zahedi has brought out a collection of his work in a new book called "Look At Me." He joins the show.