As law enforcement agencies prepare for Wednesday's inauguration, Biden told reporters he feels safe about the upcoming ceremony.

When asked at the end of a briefing on his vaccination plan Friday if he felt safe about Inauguration Day based on the intelligence he’s seen, the president-elect simply, loudly and clearly said “Yes” before exiting the room.

The FBI, DHS, Secret Service and U.S. Capitol Police, along with several local law enforcement agencies, have issued an extensive "threat assessment" surrounding Wednesday's inauguration.

There also will be 25,000 National Guardsmen in the nation’s capital to aid with security that day, ABC News has learned.

-ABC News' Molly Nagle

The Kentucky State Capitol grounds will be closed on Sunday, amid reports of threats against state capitols in the coming days, Gov. Andy Beshear announced Friday.

“Our commitment is that what happened at the U.S. Capitol will not happen here,” Beshear said in a statement.

There will be an increased law enforcement presence at the state Capitol for the next several days, including support from the Kentucky National Guard, and areas near the Capitol will be closed on Sunday, the governor said.

There are no gatherings or rallies planned in the coming days, he noted.

Biden outlined a five-point vaccination plan Friday to ramp up rollout when he takes office.

On day one, he said he plans to instruct the Federal Emergency Management Agency to start opening the first of thousands of federally supported community vaccination centers across the nation. By the end of his first month in office, 100 of these centers will be open, Biden said, at places that are "convenient and accessible," such as school gymnasiums, community centers and sports stadiums.

"As we build them, we're going to make sure it's done equitably," Biden said. "We're going to make sure there are vaccination sites in areas hit harder by the pandemic, in Black and Hispanic communities as well."

Within the first month, his administration also plans to promote mobile vaccination clinics "to hard-hit and hard-to-reach communities in cities, small towns and in rural communities," he said.

Thirdly, the administration plans to "fully activate the pharmacies across the country to get the vaccination into more arms as quickly as possible," Biden said. This will include working with both independent and chain pharmacies to help people more easily make appointments, he said.

The fourth point of the plan involves ramping up vaccine supply through the Defense Production Act, Biden said.

"We'll use the Defense Protection Act to work with private industry to accelerate the making of materials needed to supply and administer the vaccine, from tubes and syringes to protective equipment," Biden said.

Lastly, Biden promised transparency on vaccine supply.

"We're going to make sure state and local officials know how much supply they'll be getting and when they can expect to get it so they can plan," he said. "Right now, we're hearing that they can't plan, because they don't know how much supply of vaccines they can expect at what time frame."

Biden stressed that his administration is not changing the Food and Drug Administration's recommended dosing schedules.

"We believe it's critical that everyone should get two doses within the FDA-recommended time frame. So we're not doing away with that availability," he said.

Ahead of planned remarks Friday afternoon on his vaccination program, Biden released the names of top members of his White House science team.

Dr. Francis Collins will continue in his role as director of the National Institutes of Health, Biden announced.

Biden also wrote a letter to Dr. Eric Lander, the presidential science advisor-designate and nominee for director of the Office of Science and Technology Policy (OSTP), tasking him to "work broadly and transparently with the diverse scientific leadership of American society."

Here are all the positions announced Friday by the Biden team:

-Dr. Eric Lander will be nominated as director of the OSTP and serve as the presidential science advisor.

-Dr. Alondra Nelson will serve as OSTP deputy director for science and society.

-Dr. Frances H. Arnold and Dr. Maria Zuber will serve as the external co-chairs of the President’s Council of Advisors on Science and Technology.

-Dr. Francis Collins will continue serving in his role as director of the National Institutes of Health.

-Kei Koizumi will serve as OSTP chief of staff and is one of the nation’s leading experts on the federal science budget.

-Narda Jones will serve as OSTP legislative affairs director.

-ABC News' John Verhovek

House Democrats have opened an investigation into what law enforcement and the intelligence community knew about threats to the Capitol ahead of the Jan. 6 siege.

The investigation from the House Intelligence, Oversight, Homeland Security and Judiciary committees will also examine whether anyone with security clearances -- current or former National Security, Defense, Justice or Homeland Security officials -- participated in the riot.

The investigation will also examine the federal law enforcement response in the aftermath of the attack.

"The Committees will conduct robust oversight to understand what warning signs may have been missed, determine whether there were systemic failures, and consider how to best address countering domestic violent extremism, including remedying any gaps in legislation or policy," committee members wrote in a letter to the FBI, DHS and Office of the Director of National Intelligence.

"This still-emerging story is one of astounding bravery by some U.S. Capitol Police and other officers; of staggering treachery by violent criminals; and of apparent and high-level failures -- in particular, with respect to intelligence and security preparedness," the letter later stated.

Democrats plan to request documents and briefings from administration officials as part of the investigation -- just one of several looking into the Capitol attack.

-ABC News' Benjamin Siegel