Dr. Anthony Fauci explains a key mystery of COVID-19 we still don't understand

On Monday's edition of CNN's "Cuomo Prime Time," NIH infectious disease expert Dr. Anthony Fauci discussed Chris Cuomo's personal case of the disease — and illustrated a key aspect of the virus that experts still don't understand.

"The fact is you were going through some difficult times," said Fauci. "I don't think that the people who were seeing you on the show were really experiencing or realizing how you were really sucking it up to look relatively normal. But when you finished the show and we would start chatting at 11:00, 11:30 at night, you were wiped out. You not only had the acute difficulty with a virus that was replicating in you, but you had some of the secondary effects, the fever, the aches, the feeling washed out."

"And even when you were viral negative, I was concerned, because you're uncomfortable," Fauci added. "People look at you, you look pretty good right now, but boy, you put on a great act in front of the TV because you were really wiped out badly. I was worried about you there for a while because we know, I didn't want to scare you, I gave you the truth, that there is a period of time in some individuals where you look like you're recovering and then all of a sudden things go really bad."

"The reason why that happens, as you and I have discussed over the phone at night, is we're not even sure," continued Fauci. "We don't even have a full grasp of the pathogenesis of why some people do what you did. You felt bad, you felt bad, then you started getting better and better. Some people, they feel good, they feel bad, they feel bad, and then they start to feel better, and then boom, they go downhill. We need to figure out what that is, because when we do, it will help us to intervene to do something about it."

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