In the last few days, the United States ramped up COVID vaccinations after a slow start, administering about 4 million doses so far, according to federal health officials.

Dr. Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases (NIAID), said on ABC’s “This Week” that President-elect Joe Biden’s aim to administer 100 million doses within his first 100 days in office is achievable.

He went on to reject President Donald Trump’s false claim on Twitter that COVID deaths and cases in the nation have been greatly exaggerated.

Dr. Fauci told NBC, “All you need to do … is go into the trenches, go into the hospitals, go into the intensive care units and see what is happening. Those are real numbers, real people and real deaths.”

In the U.S., the death toll has climbed past 360,000, the most of any country, while over 20 million people have been infected.

L.A. Mayor Eric Garcetti said the pandemic has been getting worse in his city as the virus spreads rapidly within households and people let their guard down. He said, “This is a virus that preys off of our weakness, preys off of our exhaustion.”

Dr. Fauci said he has seen “some little glimmer of hope” after 1.5 million doses were administered in the previous 72 hours, a marked increase in vaccinations, adding that about 4 million doses have been administered.

The nation’s top infectious disease expert also acknowledged that the U.S. has fallen short of its goal of shipping and distributing 20 million doses by the end of December.

He said, “There have been a couple of glitches. That’s understandable. We are not where we want to be, there’s no doubt about that.”

However, Dr. Fauci said he is optimistic that the momentum will pick up by mid-January, vaccinating nearly 1 million people a day. He said Biden’s “goal of vaccinating 100 million people in the first 100 days is a realistic goal.”

Dr. Moncef Slaoui, Chief Science Adviser to Operation Warp Speed, told CBS that more than 17 million doses have been shipped. Dr. Fauci said around 13 million of those doses have been distributed to clinics, hospitals, and other places where they will be administered.

U.S. Surgeon General Dr. Jerome Adams said the goal of shipping 20 million doses has not been reached because local health departments and medical centers have been staying focused on testing to handle a surge in new cases.

“I don’t want anyone to think I’m being Pollyannish here,” Dr. Adams told CNN. “There’s what we delivered, and we hope that those will be translated into vaccinations. That has not occurred to the way that we would like.”

On Sunday, Trump tweeted that the outbreak has been “far exaggerated” because of the CDC’s “ridiculous” methodology. Dr. Fauci has warned that an additional surge is probably due to holiday gatherings and the cold weather keeping people indoors. “It could and likely will get worse in the next couple of weeks, or at least maintain this very terribly high level of infections and deaths that we’re seeing,” he said.