Eli Lilly announced Tuesday that the drugmaker is ooking to buy three vaccine companies in a $4 billion deal as part of an effort to expand research and development into infectious diseases. 

Under the agreed deals, Eli Lilly will buy Curevo for $1.5 billion, LimmaTech Biologics for $780 million and Vaccine Company for $1.55 billion, according to CNBC. 

Following the announcement, shares of Eli Lilly rose 0.9% shortly after markets opened. 

“These acquisitions reflect a deliberate strategy to prevent disease at its source rather than treat its consequences,” Daniel Skovronsky, chief scientific and product officer and president, said in a statement.