Workers unload containers with vaccines developed by Chinese firm Sinovac Biotech at Santiago international airport in Santiago, Chile, Jan. 28, 2021. Chilean President Sebastian Pinera on Thursday welcomed a shipment of nearly 2 million vaccines developed by Chinese firm Sinovac Biotech as the South American country is preparing for mass vaccination campaign against COVID-19. (Photo by Jorge Villegas/Xinhua)

Workers unload containers with vaccines developed by Chinese firm Sinovac Biotech at Santiago international airport in Santiago, Chile, Jan. 28, 2021. Chilean President Sebastian Pinera on Thursday welcomed a shipment of nearly 2 million vaccines developed by Chinese firm Sinovac Biotech as the South American country is preparing for mass vaccination campaign against COVID-19. (Photo by Jorge Villegas/Xinhua)

Chilean President Sebastian Pinera (3rd R) delivers a speech as he welcomes a shipment of vaccines developed by Chinese firm Sinovac Biotech at Santiago international airport in Santiago, Chile, Jan. 28, 2021. Pinera on Thursday welcomed a shipment of nearly 2 million vaccines developed by Chinese firm Sinovac Biotech as the South American country is preparing for mass vaccination campaign against COVID-19. (Photo by Jorge Villegas/Xinhua)

A worker drives a vehicle to carry containers loaded with vaccines developed by Chinese firm Sinovac Biotech at Santiago international airport in Santiago, Chile, Jan. 28, 2021. Chilean President Sebastian Pinera on Thursday welcomed a shipment of nearly 2 million vaccines developed by Chinese firm Sinovac Biotech as the South American country is preparing for mass vaccination campaign against COVID-19. (Photo by Jorge Villegas/Xinhua)

Chilean President Sebastian Pinera (3rd R) delivers a speech as he welcomes a shipment of vaccines developed by Chinese firm Sinovac Biotech at Santiago international airport in Santiago, Chile, Jan. 28, 2021. Pinera on Thursday welcomed a shipment of nearly 2 million vaccines developed by Chinese firm Sinovac Biotech as the South American country is preparing for mass vaccination campaign against COVID-19. (Photo by Jorge Villegas/Xinhua)

Chilean President Sebastian Pinera delivers a speech as he welcomes a shipment of vaccines developed by Chinese firm Sinovac Biotech at Santiago international airport in Santiago, Chile, Jan. 28, 2021. Pinera on Thursday welcomed a shipment of nearly 2 million vaccines developed by Chinese firm Sinovac Biotech as the South American country is preparing for mass vaccination campaign against COVID-19. (Photo by Jorge Villegas/Xinhua)

A worker drives a vehicle to carry containers loaded with vaccines developed by Chinese firm Sinovac Biotech at Santiago international airport in Santiago, Chile, Jan. 28, 2021. Chilean President Sebastian Pinera on Thursday welcomed a shipment of nearly 2 million vaccines developed by Chinese firm Sinovac Biotech as the South American country is preparing for mass vaccination campaign against COVID-19. (Photo by Jorge Villegas/Xinhua)