Centers for Disease Control and Prevention Director Dr. Robert Redfield holds up his mask as he speaks at a Senate Appropriations subcommittee hearing on a "Review of Coronavirus Response Efforts" on Capitol Hill, Wednesday, Sept. 16, 2020, in Washington. (AP Photo/Andrew Harnik, Pool)

Sen. Jeanne Shaheen, D-N.H.,, and Sen. Jack Reed, D-R.I., listen at a hearing with the Senate Appropriations Subcommittee on Labor, Health and Human Services, Education, and Related Agencies, on Capitol Hill in Washington, Wednesday, Sept. 16, 2020. (Anna Moneymaker/New York Times, Pool via AP)

President Donald Trump speaks during a news conference at the White House, Wednesday, Sept. 16, 2020, in Washington. (AP Photo/Evan Vucci)

Sen. Chris Murphy, D-Conn., speaks during a hearing of the Senate Appropriations Subcommittee on Labor, Health and Human Services, Education, and Related Agencies, on Capitol Hill in Washington, Wednesday, Sept. 16, 2020. (Anna Moneymaker/New York Times, Pool via AP)

President Donald Trump speaks during a news conference at the White House, Wednesday, Sept. 16, 2020, in Washington. (AP Photo/Evan Vucci)

FILE - In this May 1, 2018, file photo, Former Donald Trump campaign official Michael Caputo, left, joined by his attorney Dennis C. Vacco, leaves after being interviewed by Senate Intelligence Committee staff investigating Russian meddling in the 2016 presidential election, on Capitol Hill in Washington. A House subcommittee examining President Donald Trump’s response to the coronavirus pandemic is launching an investigation into reports that political appointees have meddled with routine government scientific data to better align with Trump’s public statements. The Democrat-led subcommittee said Sept. 14, 2020 that it is requesting transcribed interviews with seven officials from the Centers for Disease Control and Prevention and the Department of Health and Human Services, including communications aide Michael Caputo. (AP Photo/J. Scott Applewhite, File)

Centers for Disease Control and Prevention Director Dr. Robert Redfield pauses while speaking at a Senate Appropriations subcommittee hearing on a "Review of Coronavirus Response Efforts" on Capitol Hill, Wednesday, Sept. 16, 2020, in Washington. (AP Photo/Andrew Harnik, Pool)

Sen. Roy Blunt, R-Mo., speaks at a hearing with the Senate Appropriations Subcommittee on Labor, Health and Human Services, Education, and Related Agencies, on Capitol Hill in Washington, Wednesday, Sept. 16, 2020. (Anna Moneymaker/New York Times, Pool via AP)

Democratic presidential candidate former Vice President Joe Biden arrives to speak after participating in a coronavirus vaccine briefing with public health experts, Wednesday, Sept. 16, 2020, in Wilmington, Del. (AP Photo/Patrick Semansky)

Centers for Disease Control and Prevention Director Dr. Robert Redfield puts his mask back on after speaking at a Senate Appropriations subcommittee hearing on a "Review of Coronavirus Response Efforts" on Capitol Hill, Wednesday, Sept. 16, 2020, in Washington. (AP Photo/Andrew Harnik, Pool)

Democratic presidential candidate former Vice President Joe Biden speaks after participating in a coronavirus vaccine briefing with public health experts, Wednesday, Sept. 16, 2020, in Wilmington, Del. (AP Photo/Patrick Semansky)

White House coronavirus adviser Dr. Scott Atlas speaks as President Donald Trump and White House press secretary Kayleigh McEnany listen during a news conference at the White House, Wednesday, Sept. 16, 2020, in Washington. (AP Photo/Evan Vucci)

FILE - In this July 30, 2020 photo, Kai Hu, a research associate transfers medium to cells, in the laboratory at Imperial College in London. Imperial College is working on the development of a COVID-19 vaccine. In a report to Congress and an accompanying “playbook” for states and localities, key federal health agencies and the Defense Department sketched out complex plans for a vaccination campaign to begin gradually early next year or later in 2020, eventually ramping up to reach any American who wants a shot. The Pentagon is involved with the distribution of vaccines, but civilian health workers will be the ones giving shots. (AP Photo/Kirsty Wigglesworth)