South Korea announced its first coronavirus cases around the same time the U.S. did, back in January. Yet, two months later and the U.S. has 50 times more cases and almost 100 times more fatalities. CNN's Dr. Sanjay Gupta has suggested that that discrepancy is because the U.S. did not act quickly enough on its mitigation efforts.

"I think that we acted late, Jake," he told CNN host Jake Tapper on Sunday's "State of the Union."

He added that we "did not test adequately," and it allowed the virus to circulate in communities across the country.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told Tapper that Gupta's assessment was "unfair."

"You know it isn't as simple as that, Jake, I'm sorry," Fauci responded.

It's unfair to compare us to South Korea, Fauci explained, because they were able to completely shut everything down, a move that the U.S. "may not have been able to do." There were several factors to consider.

"I don't think you can say we are where we are because of one factor," Fauci said. "It's very complicated, Jake."

Fauci, a White House coronavirus task force member, conceded that "obviously" if they had started the mitigation process and social distancing earlier, lives could have been spared. But, the doctor refused to get into hypotheticals. What goes into those kinds of decisions, he argued, is "complicated."

"There was a lot of pushback about shutting things down back then," Fauci recalled.

Yet, Dr. Fauci expressed his cautious optimism that America could be turning the tide soon, as the rate of hospializations are beginning to level in hotspots like New York City. Once we get the capability to test in real time, he noted, we can begin a "gradual, rolling reentry" to normal life.