ABC News August 13, 2020

Matthew McConaughey grills Dr. Anthony Fauci in Instagram interview on COVID-19

WATCH: Dr. Fauci weighs in on back to school battle amid COVID-19 crisis

Matthew McConaughey interviewed Dr. Anthony Fauci for 40 minutes on Instagram Thursday with the fast-talking, Oscar-winning actor getting a chance to grill the nation's top infectious disease expert on COVID-19.

McConaughey rapidly fired questions at the 79-year-old doctor on everything from how concerned people should be about getting the virus from touching a door knob (not as much as sharing close physical space with someone who is infected, Fauci says) to whether Advil makes symptoms worse (it doesn't).

"OK, true-false: Sunlight kills the virus?" McConaughey asked.

"It does," Fauci replied, supporting a theory pushed by President Donald Trump. "That's the truth."

MORE: After backlash that his disinfectant 'injection' idea could be deadly, Trump claims he was being 'sarcastic'

What about letting everyone get infected so we all become immune and the disease dies out?

No way, Fauci said. That would cause big problems, particularly in America, where obesity is prevalent and related conditions like diabetes and hypertension are considered risk factors in how sick a person gets.

"If everyone contracted it ... a lot of people are going to die," Fauci said.

Pool/Getty Images
Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, removes his Washington Nationals protective mask during a House Select Subcommittee on the Coronavirus Crisis hearing on July 31, 2020, in Washington, D.C.

"The death toll would be enormous and totally unacceptable," Fauci added. "And that's the reason why we're against saying, 'Let it fly. Let everybody get infected and we'll be fine.' That's a bad idea."

Fauci also said Americans need to choose between getting to party this summer and opening schools in the fall: "You want to open the bars or you want to open the schools?"

MORE: Is COVID-19 even subject to herd immunity?

McConaughey also asked Fauci if he had millions of dollars invested in a vaccine.

Fauci laughed. "Matthew, no. I got zero! I'm a government worker. I have a government salary."

McConaughey, known for his laid-back style and often photographed shirtless, instead wore a white-collared dress shirt and glasses for the interview. He turned philosophical at points, expressing his own personal disappointment and what he said was rage with the nation's response to the pandemic.

Michael Loccisano/Getty Images, FILE | Santiago Felipe/Getty Images, FILE
Matthew McConaughey attends a file premiere on July 31, 2017, in New York. | Dr. Anthony Fauci attends a gala on Oct. 24, 2018, in New York.

"Like a lot of people, I've been more than disillusioned -- actually quite full of rage -- at how COVID has been politicized," including masks, McConaughey said.

People, he added, are "looking for identity and purpose in a big time of unknown. And man, so many people have become disillusioned with our leadership," he said. "But also so many people have fervently [clung] to the fringes of the right and left, which causes further divide a lack of unity."

By the end of their discussion, McConaughey seemed heartened by Fauci's suggestion that the nation could pull together again, because it's done it in the past after World War II and 9/11.

"This is equivalent to that, Matthew. We've got to pull together, absolutely," Fauci said.

"That's it. ... We can have our freedom and our party later. Right now, let's pull together," McConaughey said.