Dr. Anthony Fauci said Sunday that he did not anticipate the COVID-19 pandemic death toll in the United States would reach current levels, lamenting that indoor activity and holiday travel has facilitated virus transmission and calling for Americans to take the necessary public safety precautions to slow the ongoing surge.

"To have 300,000 cases in a given day, and between two and 3,000 deaths a day is just terrible," the nation's top infectious disease expert told ABC's "This Week" Co-anchor Martha Raddatz Sunday. "There's no running away from the numbers, Martha. It's something that we absolutely got to grasp and get our arms around and turn that inflection down by very intensive adherence to the public health measures, uniformly, throughout the country, with no exception."

Fauci's comments came minutes after President Donald Trump misleadingly claimed in a tweet that the numbers from the Centers for Disease Control and Prevention of infected persons and deaths in the country are "exaggerated," despite coronavirus cases continuing to increase nationwide. Even as recent data fluctuates due to inconsistent reporting over the holidays, the U.S. this weekend topped 20 million COVID-19 cases and 350,000 deaths since the onset of the pandemic 10 months ago.

"The deaths are real deaths," Fauci, the director of the National Institute of Allergy and Infectious Diseases, said, when asked by Raddatz for his response to the president's tweet. "All you need to do is go out into the trenches. Go to the hospitals and see what the health care workers are dealing with. They are under very stressful situations in many areas of the country. The hospital beds are stretched, people are running out of beds, running out of trained personnel who are exhausted."

"That's real," he continued. "That's not fake. That's real."

On "This Week," Fauci also responded to growing concerns over the speed of vaccinations in the U.S.

"Many states (are) using just a small percentage of the vaccines they have received," Raddatz said. "What's the biggest cause of this delay?"

"I think it's just trying to get a massive vaccine program started and getting off on-the-right-foot," Fauci responded, acknowledging that there have been "a couple of glitches," which he called "understandable," given the scale of the effort. But the doctor contended that recent numbers offered a "glimmer of hope."

"In the last 72 hours, they've gotten 1.5 million doses into people's arms, which is an average of about 500,000 a day, which is much better than the beginning when it was much, much less than that," Fauci said. "So we are not where we want to be, there is no doubt about that, but I think we can get there if we really accelerate, get some momentum going and see what happens as we get into the first couple of weeks of January."

As of Sunday morning, over 14 million vaccine doses have been distributed across the U.S., but only 4.2 million people have received shots, according to the CDC, prompting criticism of the government's rollout plan from both Democrats and Republicans.

"As I long feared and warned, the effort to distribute and administer the vaccine is not progressing as it should," President-elect Joe Biden said Tuesday, claiming that at the current pace, "it's going to take years -- not months -- to vaccinate the American people."

"Unlike the development of the vaccines, the vaccination process itself is falling behind," Sen. Mitt Romney, R-Utah, said in a statement Friday. "That comprehensive vaccination plans have not been developed at the federal level and sent to the states as models is as incomprehensible as it is inexcusable."

Trump noted the gap between the delivery and immunization numbers in a separate tweet Sunday morning, appearing to characterize the disparity as the effect of a successful distribution plan.

"The vaccines are being delivered to the states by the Federal Government far faster than they can be administered!" Trump wrote.

Even if the U.S. vaccination program accelerates, health experts are concerned that continued skepticism about the inoculation could prolong the pandemic. Last week, Ohio Gov. Mike DeWine reported that 60% of eligible nursing home workers were declining the vaccine; Fauci has said that upwards of 70% of the population will likely need to be immunized to achieve herd immunity.

On "This Week," Raddatz referenced that distrust of the vaccine as she pressed Fauci about his prediction that the pandemic's waning days and a sense of "normality" could arrive by the fall.

"It is totally going to depend on the uptake of vaccines," he said. "If from April, May, June, July and August, we do the kind of (increased) vaccine implementation that I'm talking about -- at least (1) million people a day and maybe more -- by the time we end the summer and get to the fall, we will have achieved that level of herd immunity that I think will get us back to some form of normality."

While looking ahead, Fauci recalled the success of a vaccination effort over 70 years ago in his home city of New York that provides a blueprint for what he believes is possible in 2021 across the U.S. In 1947, 5 million New Yorkers were immunized for smallpox in two weeks, he said.

"The goal of vaccinating 100 million people in the first 100 days is a realistic goal," Fauci noted earlier in Sunday's interview. "We can do 1 million people per day. You know we’ve done massive vaccination programs, Martha, in our history. There’s no reason why we can’t do it right now."