Dr. Anthony Fauci called President-elect Joe Biden's promise to administer 100 million COVID-19 shots in the first 100 days of his term "quite feasible" during an interview with NBC's "Today" show Friday. He said he hopes the United States can get to 70% or 80% vaccination within several months.

Part of the distribution holdup, according to Fauci, has been careful prioritization by states. "If you have a dose, give it," he urged states. "Don't be so rigid as to those early designations."

Reaching those goals, however, depends on vaccine uptake. "When a vaccine becomes available, get vaccinated,” Fauci pleaded with the public.

-ABC News' Anne Flaherty contributed to this report.

U.S. President-elect Joe Biden has chosen Dr. David Kessler, former commissioner of the Food and Drug Administration (FDA), to help lead the federal government's COVID-19 vaccine initiative.

Kessler, a pediatrician and lawyer who headed the FDA from 1999 to 1997 under the Bush and Clinton administrations, will replace Dr. Moncef Slaoui, who is the current chief science officer to Operation Warp Speed.

Biden also announced several other appointees who will join his incoming administration's COVID-19 response team.

"We are in a race against time, and we need a comprehensive strategy to quickly contain this virus," Biden said in a statement Thursday. "The individuals announced today will bolster the White House’s COVID-19 Response team and play important roles in carrying out our rescue plan and vaccination program. At a time when American families are facing numerous challenges I know these public servants will do all that is needed to build our nation back better."

There were 5,534 newly confirmed cases of COVID-19 and a record 81 deaths from the disease registered in Moscow on Thursday, according to Russia's coronavirus response headquarters.

In total, the Russian capital has reported 882,962 confirmed cases with 12,322 deaths, according to the coronavirus response headquarters.

With more than 3.4 million confirmed cases, Russia has the fourth highest cumulative total in the world, after the United States, India and Brazil, according to a real-time count kept by Johns Hopkins University.

ABC News' Alina Lobzina contributed to this report.

There were 229,386 new cases of COVID-19 confirmed in the United States on Thursday, according to a real-time count kept by Johns Hopkins University.

It's the 10th consecutive day that the country has reported more than 200,000 new cases. Thursday's tally is less than the country's all-time high of 302,506 newly confirmed infections on Jan. 2, Johns Hopkins data shows.

An additional 3,769 new deaths from COVID-19 were registered nationwide on Thursday, down from a peak of 4,462 fatalities logged on Jan. 12, according to Johns Hopkins data.

COVID-19 data may be skewed due to possible lags in reporting over the holidays followed by a potentially very large backlog.

A total of 23,314,238 people in the U.S. have been diagnosed with COVID-19 since the pandemic began, and at least 388,705 have died, according to Johns Hopkins data. The cases include people from all 50 U.S. states, Washington, D.C., and other U.S. territories as well as repatriated citizens.

Much of the country was under lockdown by the end of March as the first wave of pandemic hit. By May 20, all U.S. states had begun lifting stay-at-home orders and other restrictions put in place to curb the spread of the novel coronavirus. The day-to-day increase in the country's cases then hovered around 20,000 for a couple of weeks before shooting back up over the summer.

The numbers lingered around 40,000 to 50,000 from mid-August through early October before surging again to record levels, crossing 100,000 for the first time on Nov. 4, then reaching 200,000 on Nov. 27 before topping 300,000 on Jan. 2.

Pope Francis and his predecessor, Pope Emeritus Benedict XVI, have received their first dose of a COVID-19 vaccine, according to Vatican spokesman Matteo Bruni.

"I can confirm that as part of the Vatican City State vaccination program to date, the first dose of the COVID-19 vaccine has been administered to Pope Francis and the Pope Emeritus," Bruni said in a statement Thursday.

Francis, who turned 84 last month and had part of a lung removed when he was younger, reportedly received the shot Wednesday while Benedict, 93, reportedly got it Thursday.

Vatican City, an independent enclave surrounded by Rome that serves as the headquarters of the Roman Catholic Church, launched the immunization campaign on Wednesday, administering doses of a COVID-19 vaccine developed by U.S. pharmaceutical giant Pfizer and its German partner BioNTech.

The tiny city-state has a population of only around 800 people but employs more than 4,000. It's unclear how many doses of the Pfizer/BioNTech vaccine have been procured so far.

Vatican City citizens, along with employees and pensioners, will have the opportunity to receive the vaccine as well as family members who are entitled to use of the city-state's health care system. Priority is being given to health care workers, public safety personnel, the elderly and individuals who are most frequently in contact with the public, according to Bruni.

The vaccination campaign is voluntary and people under the age of 18 are being excluded for the time being, Bruni said.

Since the start of the pandemic, Vatican City has reported at least 27 confirmed cases of COVID-19, according to a real-time count kept by Johns Hopkins University.

ABC News' Phoebe Natanson contributed to this report.