Pune: Serum Institute of India, the world's largest vaccine manufacturer, is investing $100 million on a potential COVID-19 vaccine being developed at Oxford University, according to a company official.The Pune-based company has partnered with AstraZeneca, a British biopharma giant, to ensure equitable supply of the AZD1222 vaccine doses to India as well as low-and-middle-income countries."Our manufacturing facility is ready and we plan to start production in two months.