A health worker participating in a simulation exercise for the coronavirus disease (COVID-19) vaccination activities is pictured surrounded by members of the media, at the Universidad de Manila, in Manila, Philippines, January 19, 2021. REUTERS/Lisa Marie David

A health worker conducts mock vaccination during a simulation exercise for the coronavirus disease (COVID-19) vaccination activities, at the Universidad de Manila, in Manila, Philippines, January 19, 2021. REUTERS/Lisa Marie David

A health worker conducts mock vaccination during a simulation exercise for the coronavirus disease (COVID-19) vaccination activities, at the Universidad de Manila, in Manila, Philippines, January 19, 2021. REUTERS/Lisa Marie David

A health worker looks on during a simulation exercise for the coronavirus disease (COVID-19) vaccination activities, at the Universidad de Manila, in Manila, Philippines, January 19, 2021. REUTERS/Lisa Marie David

Merchants deliver saliva samples for a test at the Thanon Mitr Market, amid the spread of the coronavirus disease (COVID-19), in Bangkok, Thailand, January 19, 2021. REUTERS/Chalinee Thirasupa

A health worker checks the blood pressure of a woman during a simulation exercise for the coronavirus disease (COVID-19) vaccination activities, at the Universidad de Manila, in Manila, Philippines, January 19, 2021. REUTERS/Lisa Marie David

Health workers check the temperature and blood pressure of a woman during a simulation exercise for the coronavirus disease (COVID-19) vaccination activities, at the Universidad de Manila, in Manila, Philippines, January 19, 2021. REUTERS/Lisa Marie David

Merchants wait to be tested at the Thanon Mitr Market, amid the spread of the coronavirus disease (COVID-19), in Bangkok, Thailand, January 19, 2021. REUTERS/Chalinee Thirasupa

Merchants wait to be tested at the Thanon Mitr Market, amid the spread of the coronavirus disease (COVID-19), in Bangkok, Thailand, January 19, 2021. REUTERS/Chalinee Thirasupa

A woman walks past closed shops at the Thanon Mitr Market, amid the spread of the coronavirus disease (COVID-19), in Bangkok, Thailand, January 19, 2021. REUTERS/Chalinee Thirasupa

Health workers get ready to collect samples for further testing at Thanon Mitr Market, amid the spread of the coronavirus disease (COVID-19), in Bangkok, Thailand, January 19, 2021. REUTERS/Chalinee Thirasupa

A health worker organises samples collected for further testing at Thanon Mitr Market, amid the spread of the coronavirus disease (COVID-19), in Bangkok, Thailand, January 19, 2021. REUTERS/Chalinee Thirasupa

Health workers organise samples collected for further testing at Thanon Mitr Market, amid the spread of the coronavirus disease (COVID-19), in Bangkok, Thailand January 19, 2021. REUTERS/Chalinee Thirasupa

A woman walks past closed shops at Thanon Mitr Market, amid the spread of the coronavirus disease (COVID-19), in Bangkok, Thailand January 19, 2021. REUTERS/Chalinee Thirasupa

University of the Philippines President Danilo Concepcion speaks before students and activists during a protest following the defense ministry's cancellation of a decades-long pact hindering police and soldiers from the country's state university, University of the Philippines (UP), at University Avenue in Quezon City, Metro Manila, Philippines, January 19, 2021. REUTERS/Eloisa Lopez

An activist holds a placard during a protest following the defense ministry's cancellation of a decades-long pact hindering police and soldiers from the country's state university, University of the Philippines (UP), at the University Avenue in Quezon City, Metro Manila, Philippines, January 19, 2021. REUTERS/Eloisa Lopez

Students and activists stage a protest following the defense ministry's cancellation of a decades-long pact hindering police and soldiers from the country's state university, University of the Philippines (UP), at University Avenue in Quezon City, Metro Manila, Philippines, January 19, 2021. REUTERS/Eloisa Lopez

Students and activists stage a protest following the defense ministry's cancellation of a decades-long pact hindering police and soldiers from the country's state university, University of the Philippines (UP), at University Avenue in Quezon City, Metro Manila, Philippines, January 19, 2021. REUTERS/Eloisa Lopez

Students and activists stage a protest following the defense ministry's cancellation of a decades-long pact hindering police and soldiers from the country's state university, University of the Philippines (UP), at University Avenue in Quezon City, Metro Manila, Philippines, January 19, 2021. REUTERS/Eloisa Lopez

Students and activists march to protest following the defense ministry's cancellation of a decades-long pact hindering police and soldiers from the country's state university, University of the Philippines (UP), at University Avenue in Quezon City, Metro Manila, Philippines, January 19, 2021. REUTERS/Eloisa Lopez

Reuters Graphics

A vial of Pfizer-BioNTech vaccine is pictured at Gleneagles hospital's vaccination exercise for healthcare workers, during the coronavirus disease (COVID-19) outbreak, in Singapore January 19, 2021. REUTERS/Edgar Su

A nurse prepares to vaccinate healthcare workers at Gleneagles hospital, during the coronavirus disease (COVID-19) outbreak, in Singapore January 19, 2021. REUTERS/Edgar Su

A nurse prepares to vaccinate healthcare workers at Gleneagles hospital, during the coronavirus disease (COVID-19) outbreak, in Singapore January 19, 2021. REUTERS/Edgar Su

A doctor is vaccinated at Gleneagles hospital, during the coronavirus disease (COVID-19) outbreak, in Singapore January 19, 2021. REUTERS/Edgar Su

Soldiers take part in a drill in a military base ahead of the Chinese New year in Hsinchu, Taiwan, January 19, 2021. REUTERS/Ann Wang

Soldiers take part in a drill in a military base ahead of the Chinese New year in Hsinchu, Taiwan, January 19, 2021. REUTERS/Ann Wang

Armed vehicles take part in a drill in a military base ahead of the Chinese New year in Hsinchu, Taiwan, January 19, 2021. REUTERS/Ann Wang

Soldiers wait to take part in a drill in a military base ahead of the Chinese New year in Hsinchu, Taiwan, January 19, 2021. REUTERS/Ann Wang

Soldiers take part in a drill in a military base ahead of the Chinese New year in Hsinchu, Taiwan, January 19, 2021. REUTERS/Ann Wang

Soldiers take part in a drill in a military base ahead of the Chinese New year in Hsinchu, Taiwan, January 19, 2021. REUTERS/Ann Wang

Members of the media take photos of a military drill ahead of the Chinese New year in Hsinchu, Taiwan, January 19, 2021. REUTERS/Ann Wang

Armed vehicles take part in a drill in a military base ahead of the Chinese New year in Hsinchu, Taiwan, January 19, 2021. REUTERS/Ann Wang

Armed vehicles take part in a drill in a military base ahead of the Chinese New year in Hsinchu, Taiwan, January 19, 2021. REUTERS/Ann Wang

Soldiers take part in a drill in a military base ahead of the Chinese New year in Hsinchu, Taiwan, January 19, 2021. REUTERS/Ann Wang

Members of the U.S. National Guard march on patrol on a nearly empty street past boarded-up buildings, days ahead of U.S. President-elect Joe Biden's inauguration, in Washington, D.C., U.S. January 18, 2021. REUTERS/Mike Segar

A U.S. National Guard member patrols on a nearly empty street, days ahead of U.S. President-elect Joe Biden's inauguration, in Washington, D.C., U.S. January 18, 2021. REUTERS/Mike Segar

An illuminated and barricaded checkpoint is seen on a nearly empty and closed street, days ahead of U.S. President-elect Joe Biden's inauguration, in Washington, D.C., U.S. January 18, 2021. REUTERS/Mike Segar

Members of the U.S. National Guard run as they patrol on a nearly empty street past boarded up buildings, days ahead of U.S. President-elect Joe Biden's inauguration, in Washington, D.C., U.S. January 18, 2021. REUTERS/Mike Segar

People wearing face masks following the coronavirus disease (COVID-19) outbreak are seen on a snowy day in Beijing, China January 19, 2021. REUTERS/Tingshu Wang

A woman wearing a face mask following the coronavirus disease (COVID-19) outbreak, rides a bicycle on the street during a snowy morning in Beijing, China, January 19, 2021. REUTERS/Carlos Garcia Rawlins

A worker removes snow from the sidewalk next to people walking during a snowy morning in Beijing, China, January 19, 2021. REUTERS/Carlos Garcia Rawlins

A woman wearing a face mask following the coronavirus disease (COVID-19) outbreak, walks on the street during a snowy morning in Beijing, China, January 19, 2021. REUTERS/Carlos Garcia Rawlins

A jogger wearing a face mask following the coronavirus disease (COVID-19) outbreak, runs through the snow in Beijing, China, January 19, 2021. REUTERS/Carlos Garcia Rawlins

A migrant, part of the caravan of Central Americans, stands outside a migrant shelter in Tecun Uman, Guatemala January 18, 2021. REUTERS/Carlos Jasso

Migrants from Honduras, part of the caravan of Central Americans stand outside a migrant shelter in Tecun Uman, Guatemala January 18, 2021. REUTERS/Carlos Jasso

A child rides a bicycle on a snow-covered frozen river, on a snowy day in Beijing, China January 19, 2021. REUTERS/Tingshu Wang

A police officer checks documentation from passengers inside a bus, to check for migrants coming from the caravan of Central Americans, to prevent them from continuing their journey to the U.S, at a checkpoint, in Pajapita, Guatemala January 18, 2021. REUTERS/Carlos Jasso

A child rides a bicycle on a snow-covered frozen river, on a snowy day in Beijing, China January 19, 2021. REUTERS/Tingshu Wang REFILE - CORRECTING YEAR

An immigration agent keeps watch at the banks of the Suchiate river, the natural border between Mexico and Guatemala, to guard the border and prevent a migrant caravan of Central Americans from entering, in Ciudad Hidalgo, Mexico January 18, 2021. REUTERS/Carlos Jasso

Members of the National Guard keep watch at the banks of the Suchiate river, the natural border between Mexico and Guatemala, to guard the border and prevent a migrant caravan of Central Americans from entering, in Ciudad Hidalgo, Mexico January 18, 2021. REUTERS/Carlos Jasso

A Meituan delivery worker rides a scooter carrying vegetables on a snowy day in Beijing, China January 19, 2021. REUTERS/Tingshu Wang

Police officers interrogate a man for documentation as they look over migrants coming from the caravan of Central Americans, to prevent them from continuing their journey to the U.S, at a checkpoint, in Pajapita, Guatemala January 18, 2021. REUTERS/Carlos Jasso

Vanderlecia Ortega dos Santos, or Vanda, from the Witoto indigenous tribe, receives the Sinovac coronavirus disease (COVID-19) vaccine, in Manaus, Brazil January 18, 2021. REUTERS/Bruno Kelly

Vanderlecia Ortega dos Santos, or Vanda, from the Witoto indigenous tribe, is greeted by Amazonas Governor Wilson Lima after receiving the Sinovac coronavirus disease (COVID-19) vaccine, in Manaus, Brazil January 18, 2021. REUTERS/Bruno Kelly

A person wearing a face mask following the coronavirus disease (COVID-19) outbreak, pushes a child in a pram on a snowy day in Beijing, China January 19, 2021. REUTERS/Tingshu Wang

A police officer is seen as he prepares to check the documentation of the passengers to look over for migrants coming from the caravan of Central Americans, to prevent them from continuing their journey to the U.S, at a checkpoint, in Pajapita, Guatemala January 18, 2021. REUTERS/Carlos Jasso

Vanderlecia Ortega dos Santos, or Vanda, from the Witoto indigenous tribe, receives the Sinovac coronavirus disease (COVID-19) vaccine in Manaus, Brazil January 18, 2021. REUTERS/Bruno Kelly

A police officer examines the documentation of the passengers to check for migrants coming from the caravan of Central Americans, to prevent them from continuing their journey to the U.S, at a checkpoint, in Pajapita, Guatemala January 18, 2021. REUTERS/Carlos Jasso

People wearing face masks following the coronavirus disease (COVID-19) outbreak are seen on a snowy day in Beijing, China January 19, 2021. REUTERS/Tingshu Wang