The world’s largest vaccine maker is ramping up production of AstraZeneca Plc’s Covid-19 shot, aiming to have 100 million doses ready by December for an inoculation drive that could begin across India that same month. If final-stage trial data show AstraZeneca’s candidate gives effective protection from the virus, the Serum Institute of India Ltd. — which is partnered to produce at least one billion doses — may get emergency authorization from New Delhi by December, said Adar Poonawalla, chief executive officer of the family-owned firm based in the western city of Pune. That initial amount will go to India, Poonawalla said in an interview on Thursday. Full approval early next year will allow distribution on a 50-50 basis with the South Asian nation and Covax, the World Health Organization-backed body that’s purchasing shots for poor nations. Serum, which has tied up with five developers, has so far made 40 million doses of AstraZeneca’s vaccine in the past two months and aims to start manufacturing Novavax Inc.’s contender soon.