In this Wednesday, June 24, 2020, file photo, a volunteer receives an injection at the Chris Hani Baragwanath hospital in Soweto, Johannesburg, as part of Africa’s first participation in a COVID-19 vaccine trial developed at the University of Oxford in Britain in conjunction with the pharmaceutical company AstraZeneca. AstraZeneca says late-stage trials of its COVID-19 vaccine were “highly effective” in preventing disease. A vaccine developed by AstraZeneca and the University of Oxford prevented 70% of people from developing the coronavirus in late-stage trials, the team reported Monday Nov. 23, 2020. (Siphiwe Sibeko/Pool via AP)