When Pfizer was searching for a major acquisition in 2009, it saw a lot it liked in Wyeth--including an established vaccine group that could jump-start its own efforts in that area. Pfizer had a nascent vaccine group was doing research but it didn't have any products on the market. After the buy, the world's largest drugmaker found itself with a pipeline of new vaccine candidates and another valuable asset: Dr. Emilio Emini, a noted vaccine researcher who spent 22 years at Merck doing HIV research and working on such blockbusters products as Zostavax, RotaTeq and Gardasil. After retiring from the company in 2004 to pursue nonprofit work, he joined Wyeth a year later to take charge of the company's vaccine research. When Pfizer and Wyeth joined, Emini found himself at the head of the new vaccine division. The combined group now has "hundreds" of employees, and in excess of $3.6 billion in annual sales, roughly $2.4 billion of which comes from Prevnar-13. But Pfizer has even bigger plans for its vaccine division. Read the interview