South Africa’s vaccine rollout took a step back over the weekend. Yesterday, the country paused its distribution of the AstraZeneca-Oxford coronavirus vaccine. This comes after evidence emerged from a new study that the vaccine doesn’t appear to protect against mild and moderate illness from a fast-spreading new strain of the coronavirus, first detected in South Africa. Host Marco Werman talks with Dr. Barry Bloom, professor of immunology and infectious diseases at Harvard’s T.H. Chan School of Public Health.