Mumbai: 'Vaccine king' Cyrus Poonawalla's wealth grew the fastest, at $15 billion, among Indian billionaires and fifth fastest in the world during the COVID-19 pandemic because of the strong business potential of his company, Serum Institute of India, according to a report by Hurun Research.Poonawalla has climbed 57 places to be the 86th richest person in the world as of May 31 on the back of a 25 per cent rise in his net worth during the four months of the pandemic, the report said.The Pune-based entrepreneur's unlisted company is already the largest vaccine manufacturer in the world and the net worth has been helped by vaccine distribution and manufacturing potential of his business, it added.Recently, Serum struck an agreement with.