For Walensky, one of the key signs the United States is exiting the pandemic will be when hospitals are no longer filled to the brim with COVID-19 patients. And when the number of daily deaths starts to plummet.
"We've gotten pretty cavalier about 1,100 deaths a day," Walensky told ABC News Chief Medical Correspondent Dr. Jennifer Ashton in a rare in-person interview from CDC headquarters in Atlanta.
"That's an extraordinary amount of deaths in a single day from this disease," Walensky said. "We can't -- I can't -- be in a position where that is OK."
For the nation's public health experts, deaths and hospitalizations have become a more reliable benchmark for progress than overall cases.
Dr. Jennifer Ashton, ABC News' chief medical correspondent, was given rare access inside the Centers for Disease Control and Prevention's Emergency Operations Center in Atlanta by CDC Director Dr. Rochelle Walensky. (Matt Miller/ABC)
The more scientists have learned about the virus, the more they have moved away from concept of herd immunity -- the idea that the virus will one day be stopped in its tracks when enough people are immune.
Instead, scientists agree that some mild breakthrough cases are still likely to happen, even among the vaccinated. In a world where almost everyone was vaccinated, COVID-19 cases would still happen.
The virus would still spread among us, akin to the seasonal flu. And like the flu, some people would still be hospitalized, and some would die -- but dramatically fewer than 1,100 deaths per day.
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Right now, roughly 65% of eligible Americans are fully vaccinated, according to the CDC. The more people who get vaccinated, the more deaths and hospitalizations are driven down.
The CDC's real-world data is already demonstrating this to be true, with unvaccinated people 14 times more likely to die and 11 times more likely to be hospitalized with COVID-19.
Despite the grim daily death count, Walensky said she believes that one day we'll leave behind one of the key symbols of the pandemic: the face mask.
"Masks are for now, they're not forever," Walensky said. "We have to find a way to be done with them."
And the best way to put the pandemic -- and masks -- in the rearview mirror is to "lean in" to the current strategies we know work, Walensky said.
And for now, Walensky is urging patience as public health guidance evolves to reflect new science.
"Science is hard in a two-minute soundbite," she said. "Know that every single decision -- as hard as they are -- have been grounded in science."