The AstraZeneca vaccine and our ongoing uncertainty problem

On Sunday, Shabir Madhi, a vaccines expert in Johannesburg, went on South African TV and shared news from a study he had been working on: the vaccine developed by AstraZeneca and researchers at Oxford University, he said, appears not to be very effective at preventing mild to moderate cases of the coronavirus variant that has become dominant in his country. The finding, which led the South African government to temporarily stop rolling out the AstraZeneca vaccine, echoed in grim headlines...