People wearing face masks commute in a subway station during morning rush hour, following the coronavirus disease ( COVID-19) outbreak, in Beijing, China January 20, 2021. REUTERS/Tingshu Wang

People wearing face masks commute in a subway station during morning rush hour, following the coronavirus disease ( COVID-19) outbreak, in Beijing, China January 20, 2021. REUTERS/Tingshu Wang

People wearing face masks commute in a subway station during morning rush hour, following the coronavirus disease ( COVID-19) outbreak, in Beijing, China January 20, 2021. REUTERS/Tingshu Wang

People wearing face masks commute in a subway station during morning rush hour, following the coronavirus disease ( COVID-19) outbreak, in Beijing, China January 20, 2021. REUTERS/Tingshu Wang

People wearing face masks commute in a subway station during morning rush hour, following the coronavirus disease ( COVID-19) outbreak, in Beijing, China January 20, 2021. REUTERS/Tingshu Wang

A man stands outside an entrance of Beijing North Railway Station during morning rush hour, following the coronavirus disease ( COVID-19) outbreak, in Beijing, China January 20, 2021. REUTERS/Tingshu Wang

People wearing face masks commute in a subway station during morning rush hour, following the coronavirus disease ( COVID-19) outbreak, in Beijing, China January 20, 2021. REUTERS/Tingshu Wang

People wearing face masks commute in a subway station during morning rush hour, following the coronavirus disease ( COVID-19) outbreak, in Beijing, China January 20, 2021. REUTERS/Tingshu Wang

People wearing face masks commute in a subway station during morning rush hour, following the coronavirus disease ( COVID-19) outbreak, in Beijing, China January 20, 2021. REUTERS/Tingshu Wang

People wearing face masks commute in a subway station during morning rush hour, following the coronavirus disease ( COVID-19) outbreak, in Beijing, China January 20, 2021. REUTERS/Tingshu Wang

People wearing face masks travel at a subway station during morning rush hour, following the coronavirus disease ( COVID-19) outbreak, in Beijing, China January 20, 2021. REUTERS/Tingshu Wang

The "Field of Flags" and the Washington Monument are seen from behind fences at the National Mall ahead of inauguration ceremonies for U.S. President-elect Joe Biden in Washington, U.S., January 19, 2021. REUTERS/Allison Shelley

The "Field of Flags" and the Washington Monument are seen from behind fences at the National Mall ahead of inauguration ceremonies for U.S. President-elect Joe Biden in Washington, U.S., January 19, 2021. REUTERS/Allison Shelley

The Empire State Building is illuminated in red to honor the lives lost to the coronavirus disease (COVID-19) continues in the Manhattan borough of New York, U.S., January 19, 2021. REUTERS/Shannon Stapleton

The Empire State Building is illuminated in red to honor the lives lost to the coronavirus disease (COVID-19) continues seen from the Queens borough of New York, U.S., January 19, 2021. REUTERS/Shannon Stapleton TPX IMAGES OF THE DAY

The Empire State Building is illuminated in red to honor the lives lost to the coronavirus disease (COVID-19) continues in the Manhattan borough of New York, U.S., January 19, 2021. REUTERS/Shannon Stapleton

President-elect Joe Biden hosts a memorial to honor those who died from coronavirus disease (COVID-19) at the reflecting pool at the Lincoln Memorial, in Washington, U.S., January 19, 2021. REUTERS/Callaghan O'Hare

The One World Trade Center building is illuminated in red to honor the lives lost to the coronavirus disease (COVID-19) as the U.S. flag blows in the wind in the Manhattan borough of New York, U.S., January 19, 2021. REUTERS/Shannon Stapleton

The Empire State Building is illuminated in red to honor the lives lost to the coronavirus disease (COVID-19) continues in the Manhattan borough of New York, U.S., January 19, 2021. REUTERS/Shannon Stapleton

Research associate Wei Li places mice with KAT7 intervention on a treadmill in the animal facility at the Institute for Stem Cell and Regeneration of the Chinese Academy of Sciences (CAS) in Beijing, China, January 12, 2021. Picture taken January 12, 2021. REUTERS/Tingshu Wang

Dr. Shuhui Sun performs a step of histological staining of mouse liver for pathological analysis in the Aging and Regeneration lab at the Institute for Stem Cell and Regeneration of the Chinese Academy of Sciences (CAS) in Beijing, China, January 12, 2021. Picture taken January 12, 2021. REUTERS/Tingshu Wang

The Empire State Building is illuminated in red to honor the lives lost to the coronavirus disease (COVID-19) continues in the Manhattan borough of New York, U.S., January 19, 2021. REUTERS/Shannon Stapleton

Researchers work in the Aging and Regeneration lab at the Institute for Stem Cell and Regeneration of the Chinese Academy of Sciences (CAS) in Beijing, China, January 12, 2021. Picture taken January 12, 2021. REUTERS/Tingshu Wang

Dr. Shuhui Sun performs histological staining of mouse liver for pathological analysis in the Aging and Regeneration lab at the Institute for Stem Cell and Regeneration of the Chinese Academy of Sciences (CAS) in Beijing, China, January 12, 2021. Picture taken January 12, 2021. REUTERS/Tingshu Wang

The nameplate for the Aging and Regeneration laboratory is seen at the Institute for Stem Cell and Regeneration of the Chinese Academy of Sciences (CAS) in Beijing, China, January 12, 2021. Picture taken January 12, 2021. REUTERS/Tingshu Wang

Dr. Jing Qu (R), team leader for Stem Cell and Ageing group, and Dr. Wei Wang discuss the work on genome-wide screen for novel ageing regulatory genes in human stem cells at the cell culture room of the Aging and Regeneration lab at the Institute for Stem Cell and Regeneration of the Chinese Academy of Sciences (CAS) in Beijing, China, January 12, 2021. Picture taken January 12, 2021. REUTERS/Tingshu Wang

A researcher cultures mesenchymal progenitor cells in the cell culture room of Aging and Regeneration lab at the Institute for Stem Cell and Regeneration of the Chinese Academy of Sciences (CAS) in Beijing, China, January 12, 2021. Picture taken January 12, 2021. REUTERS/Tingshu Wang

A researcher observes the confocal image on a screen showing the nucleus of human stem cells after KAT7 intervention, in the Aging and Regeneration lab at the Institute for Stem Cell and Regeneration of the Chinese Academy of Sciences (CAS) in Beijing, China, January 12, 2021. Picture taken January 12, 2021. REUTERS/Tingshu Wang

Researchers collect the mesenchymal progenitor cells in tubes for the following cell culture in the cell culture room of the Aging and Regeneration lab at the Institute for Stem Cell and Regeneration of the Chinese Academy of Sciences (CAS) in Beijing, China, January 12, 2021. Picture taken January 12, 2021. REUTERS/Tingshu Wang

Dr. Shuhui Sun performs a step of histological staining of mouse liver for pathological analysis in the Aging and Regeneration lab at the Institute for Stem Cell and Regeneration of the Chinese Academy of Sciences (CAS) in Beijing, China, January 12, 2021. Picture taken January 12, 2021. REUTERS/Tingshu Wang

The Empire State Building is illuminated in red to honor the lives lost to the coronavirus disease (COVID-19) continues in the Manhattan borough of New York, U.S., January 19, 2021. REUTERS/Shannon Stapleton

The One World Trade Center building is illuminated in red to honor the lives lost to the coronavirus disease (COVID-19) as the U.S. flag blows in the wind in the Manhattan borough of New York, U.S., January 19, 2021. REUTERS/Shannon Stapleton

The One World Trade Center building is illuminated in red to honor the lives lost to the coronavirus disease (COVID-19) as a Covid-19 vaccine advertisement is seen at subway stop in the Manhattan borough of New York, U.S., January 19, 2021. REUTERS/Shannon Stapleton

Charts of Netflix membership growth

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors players celebrate with the trophy Pool via REUTERS/Agustin Marcarian TPX IMAGES OF THE DAY

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors' Yamila Rodriguez and teammates celebrate with the trophy Pool via REUTERS/Juan Ignacio Roncoroni TPX IMAGES OF THE DAY

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors' Yamila Rodriguez and teammates celebrate with the trophy Pool via REUTERS/Juan Ignacio Roncoroni

Police officers patrol outside accommodations where tennis players are undergoing mandatory quarantine in advance of the Australian Open in Melbourne, Australia, January 20, 2021. REUTERS/Sandra Sanders

A tennis player undergoing mandatory quarantine enters a restricted training area in advance of the Australian Open in Melbourne, Australia, January 20, 2021. REUTERS/Sandra Sanders

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors' Yamila Rodriguez and teammates celebrate with the trophy Pool via REUTERS/Juan Ignacio Roncoroni

A tennis player undergoing mandatory quarantine enters a restricted training area in advance of the Australian Open in Melbourne, Australia, January 20, 2021. REUTERS/Sandra Sanders

Tennis players and support staff walk from accommodations where they are undergoing mandatory quarantine to train at a nearby facility in advance of the Australian Open in Melbourne, Australia, January 20, 2021. REUTERS/Sandra Sanders

A man looks out of a window of accommodations where tennis players and support staff are undergoing mandatory quarantine in advance of the Australian Open in Melbourne, Australia, January 20, 2021. REUTERS/Sandra Sanders

Paramedics load a man into an ambulance outside accommodations where tennis players and support staff are undergoing mandatory quarantine in advance of the Australian Open in Melbourne, Australia, January 20, 2021. REUTERS/Sandra Sanders

Paramedics load a man into an ambulance outside accommodations where tennis players and support staff are undergoing mandatory quarantine in advance of the Australian Open in Melbourne, Australia, January 20, 2021. REUTERS/Sandra Sanders

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors players celebrate with the trophy Pool via REUTERS/Juan Ignacio Roncoroni

Tennis coach Rohan Fisher is escorted from accommodations where players and support staff are undergoing mandatory quarantine to a nearby training facility in advance of the Australian Open in Melbourne, Australia, January 20, 2021. REUTERS/Sandra Sanders

A woman is escorted from accommodations where tennis players and support staff are undergoing mandatory quarantine to a nearby training facility in advance of the Australian Open in Melbourne, Australia, January 20, 2021. REUTERS/Sandra Sanders

A paramedic arrives at accommodations where tennis players and support staff are undergoing mandatory quarantine in advance of the Australian Open in Melbourne, Australia, January 20, 2021. REUTERS/Sandra Sanders

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors players celebrate with the trophy Pool via REUTERS/Agustin Marcarian

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 General view after the match Pool via REUTERS/Agustin Marcarian

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors players celebrate with the trophy Pool via REUTERS/Agustin Marcarian

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors players celebrate after the match Pool via REUTERS/Juan Ignacio Roncoroni

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors' Julieta Cruz celebrates with teammates after the match Pool via REUTERS/Juan Ignacio Roncoroni

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors players celebrate after the match Pool via REUTERS/Juan Ignacio Roncoroni

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors' Julieta Cruz celebrates with teammates after the match Pool via REUTERS/Juan Ignacio Roncoroni

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors' Yamila Rodriguez and teammates celebrate with the trophy Pool via REUTERS/Juan Ignacio Roncoroni

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors' Yamila Rodriguez and teammates celebrate with the trophy Pool via REUTERS/Juan Ignacio Roncoroni

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors players celebrate after the match Pool via REUTERS/Juan Ignacio Roncoroni

Soccer Football - Primera A - Final - Boca Juniors v River Plate - Estadio Jose Amalfitani, Buenos Aires, Argentina - January 19, 2021 Boca Juniors' Fanny Rodriguez celebrates with teammates after the match Pool via REUTERS/Juan Ignacio Roncoroni

Senator Michael Bennet, D-Colo., listens during a Senate Finance Committee hearing for Janet Yellen, of California, President-elect Joe Biden's nominee for Treasury Secretary in Washington, U.S., January 19, 2021. Anna Moneymaker/Pool via REUTERS

Janet Yellen, President-elect Joe Biden's nominee for Secretary of the Treasury, participates remotely in a Senate Finance Committee hearing in Washington, U.S., January 19th, 2021. Anna Moneymaker/Pool via REUTERS

Senator Mike Crapo, R-Idaho, listens during a Senate Finance Committee hearing for Janet Yellen, of California, President-elect Joe Biden's nominee for Treasury Secretary in Washington, U.S., January 19, 2021. Anna Moneymaker/Pool via REUTERS

Senator Tim Scott, R-S.C., participates remotely during a Senate Finance Committee hearing for Janet Yellen, of California, President-elect Joe Biden's nominee for Treasury Secretary in Washington, U.S., January 19, 2021. Anna Moneymaker/Pool via REUTERS

An iPhone is held up to film the timer in the Senate Finance Committee hearing for Janet Yellen, of California, President-elect Joe Biden’s nominee for Treasury Secretary in Washington, U.S., January 19, 2021. Anna Moneymaker/Pool via REUTERS

Ranking Member Ron Wyden (D-OR) speaks during a Senate Finance Committee hearing to examine the expected nomination of Janet Yellen to be Secretary of the Treasury on Capitol Hill in Washington, U.S., January 19, 2021. Andrew Harnik/Pool via REUTERS

Senator Ben Sasse, R-Neb., departs a Senate Finance Committee hearing for Janet Yellen, of California, President-elect Joe Biden's nominee for Treasury Secretary in Washington, U.S., January 19, 2021. Anna Moneymaker/Pool via REUTERS

Senator Dianne Feinstein, D-Calif., speaks during a Senate Finance Committee hearing for Janet Yellen, of California, President-elect Joe Biden's nominee for Treasury Secretary in Washington, U.S., January 19, 2021. Anna Moneymaker/Pool via REUTERS

Senator Ben Sasse, R-Neb., listens during a Senate Finance Committee hearing for Janet Yellen, of California, President-elect Joe Biden's nominee for Treasury Secretary in Washington, U.S., January 19, 2021. Anna Moneymaker/Pool via REUTERS

Senator Maria Cantwell, D-Wash., speaks to Senator Sheldon Whitehouse, D-R.I., before the start of a Senate Finance Committee hearing for Janet Yellen, of California, President-elect Joe Biden's nominee for Treasury Secretary in Washington, U.S., January 19, 2021. Anna Moneymaker/Pool via REUTERS

Chairman Sen. Chuck Grassley (R-IA) speaks during a Senate Finance Committee hearing to examine the expected nomination of Janet Yellen to be Secretary of the Treasury on Capitol Hill in Washington, U.S., January 19, 2021. Andrew Harnik/Pool via REUTERS

Chairman Sen. Chuck Grassley (R-IA) takes his seat for a Senate Finance Committee hearing to examine the expected nomination of Janet Yellen to be Secretary of the Treasury on Capitol Hill in Washington, U.S., January 19, 2021. Andrew Harnik/Pool via REUTERS

Senator Maria Cantwell, D-Wash., listens during a Senate Finance Committee hearing for Janet Yellen, of California, President-elect Joe Biden's nominee for Treasury Secretary in Washington, U.S., January 19, 2021. Anna Moneymaker/Pool via REUTERS

Senator John Thune, R-S.D., listens during a Senate Finance Committee hearing for Janet Yellen, of California, President-elect Joe Biden's nominee for Treasury Secretary in Washington, U.S., January 19, 2021. Anna Moneymaker/Pool via REUTERS

Senator Ben Sasse, R-Neb., listens during a Senate Finance Committee hearing for Janet Yellen, of California, President-elect Joe Biden's nominee for Treasury Secretary in Washington, U.S., January 19, 2021. Anna Moneymaker/Pool via REUTERS

Senator John Thune (R-SD) appears during a Senate Finance Committee hearing to examine the expected nomination of Janet Yellen to be Secretary of the Treasury on Capitol Hill in Washington, U.S., January 19, 2021. Andrew Harnik/Pool via REUTERS

Ranking Member Ron Wyden (D-OR) and Chairman Sen. Chuck Grassley (R-IA) speak together before the start of a Senate Finance Committee hearing to examine the expected nomination of Janet Yellen to be Secretary of the Treasury on Capitol Hill in Washington, U.S., January 19, 2021. Andrew Harnik/Pool via REUTERS

Senator Ben Sasse, R-Neb., arrives to a Senate Finance Committee hearing for Janet Yellen, of California, President-elect Joe Biden's nominee for Treasury Secretary in Washington, U.S., January 19, 2021. Anna Moneymaker/Pool via REUTERS