Serum Institute of India, one of the largest vaccine makers in the world, struck deals early in the pandemic to make hundreds of millions of doses for India and the developing world. In an interview with The Washington Post last year, Adar Poonawalla, the firm's chief executive, said the company hoped to boost its production of the AstraZeneca vaccine to 80 million to 100 million doses a month by the start of 2021.