1 of 5 FILE - In this Wednesday, Dec. 30, 2020 file photo, a medical worker prepares a shot of Russia s Sputnik V coronavirus vaccine in Moscow, Russia. Russian scientists say the country s Sputnik V vaccine appears safe and effective against COVID-19, according to early results of an advanced study published on Tuesday Feb. 2, 2021, in a British medical journal. (AP Photo/Pavel Golovkin, File)
2 of 5 A healthcare worker prepares a dose of Russia s Sputnik V COVID-19 vaccine, at the Del Norte Hospital in El Alto, Bolivia, Saturday, Jan. 30, 2021. (AP Photo/Juan Karita)
3 of 5 People stand in a queue to get a shot of Russia s Sputnik V coronavirus vaccine in a vaccination center in GUM State Department store in Moscow, Russia, Wednesday, Jan. 20, 2021. Russia started a mass coronavirus vaccination campaign on Monday, Jan. 18. (AP Photo/Pavel Golovkin)
Britain’s health chief has hailed a new study suggesting that a single dose of the Oxford-AstraZeneca COVID-19 vaccine provides a high level of protection for 12 weeks
1 of 6 Police officers detain supporters of Bogazici University students following a protest in Istanbul, Thursday, Feb. 4, 2021. For weeks, students and faculty members of Bogazici University have been protesting Turkey s President Recep Tayyip Erdogan s Jan. 1 appointment as a rector of Melih Bulu, an academic who once ran for parliament as a candidate for Erdogan s party. Some of the protests have erupted into clashes between police and demonstrators and hundreds of people have been detained, some taken away following raids of their homes. (AP Photo/Emrah Gurel)
2 of 6 Plainclothes police officers detain a supporter of Bogazici University students in Istanbul, Thursday, Feb. 4, 2021. For weeks, students and faculty members of Bogazici University have been protesting Turkey s President Recep Tayyip Erdogan s Jan. 1 appointment as a rector of Melih Bulu, an academic who once ran for parliament as a candidate for Erdogan s party. Some of the protests h
1 of 23 Nurses give health workers shots of Russia s Sputnik V COVID-19 vaccine at River Plate stadium in Buenos Aires, Argentina, Tuesday, Feb. 2, 2021. (AP Photo/Natacha Pisarenko)
2 of 23 A man wearing a protective mask walks by El Cano pub with a sign to encourage people to visit the pub and terrace in Madrid, Spain, Tuesday, Feb. 2, 2021. Spain s virus expert for the coronavirus pandemic says infections in the country are losing steam but that the contagion curve needs to be bent much further to safeguard the health system. (AP Photo/Paul White)
3 of 23 FILE - In this July 11, 2020, file photo, party members have their temperature checked and sanitize their hands as a precaution against the coronavirus at the national congress of the ruling Chama cha Mapinduzi (CCM) party in Dodoma, Tanzania. Tanzania s President John Magufuli openly expressed doubt about COVID-19 vaccines and accused people who were vaccinated outside the East Af