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A nurse prepares a dose of the Pfizer-BioNTech COVID-19 vaccine at the Santa Maria Hospital in Lisbon, Portugal, Dec. 27, 2020. (Photo by Pedro Fiuza/Xinhua)
A nurse prepares a dose of the Pfizer-BioNTech COVID-19 vaccine at the Santa Maria Hospital in Lisbon, Portugal, Dec. 27, 2020. (Photo by Pedro Fiuza/Xinhua)