A medical worker receives a shot of the COVID-19 vaccine in Buenos Aires, Argentina, Dec. 29, 2020. Argentina on Tuesday launched its vaccination campaign against the novel coronavirus disease (COVID-19), prioritizing healthcare workers on the frontlines of the pandemic. Two doctors, Francisco Traverso and Flavia Loiacono, were the first people to be immunized with one of 300,000 doses of the Russian Sputnik V vaccine that arrived last week. (Photo by Martin Zabala/Xinhua)

A medical worker receives a shot of the COVID-19 vaccine in Buenos Aires, Argentina, Dec. 29, 2020. Argentina on Tuesday launched its vaccination campaign against the novel coronavirus disease (COVID-19), prioritizing healthcare workers on the frontlines of the pandemic. Two doctors, Francisco Traverso and Flavia Loiacono, were the first people to be immunized with one of 300,000 doses of the Russian Sputnik V vaccine that arrived last week. (Photo by Martin Zabala/Xinhua)

A medical worker shows her vaccination card after receiving a shot of the COVID-19 vaccine in Buenos Aires, Argentina, Dec. 29, 2020. Argentina on Tuesday launched its vaccination campaign against the novel coronavirus disease (COVID-19), prioritizing healthcare workers on the frontlines of the pandemic. Two doctors, Francisco Traverso and Flavia Loiacono, were the first people to be immunized with one of 300,000 doses of the Russian Sputnik V vaccine that arrived last week. (Photo by Martin Zabala/Xinhua)

A medical worker receives a shot of the COVID-19 vaccine in Buenos Aires, Argentina, Dec. 29, 2020. Argentina on Tuesday launched its vaccination campaign against the novel coronavirus disease (COVID-19), prioritizing healthcare workers on the frontlines of the pandemic. Two doctors, Francisco Traverso and Flavia Loiacono, were the first people to be immunized with one of 300,000 doses of the Russian Sputnik V vaccine that arrived last week. (Photo by Martin Zabala/Xinhua)