When the coronavirus hit, the Serum Institute of India, the world’s largest vaccine maker, seemed uniquely positioned to help. It struck a deal with AstraZeneca, promising a billion vaccine doses to low- and middle-income nations. Earlier this year, a ban instituted by Prime Minister Narendra Modi put a stop to those plans. What has that meant for the nations promised millions of doses? Guest: Emily Schmall, a South Asia correspondent for The New York Times based in New Delhi.