** Shares of drugmaker Eli Lilly LLY.N rise 1.5% to $1,081 premarket

** Co says it will buy three privately-held vaccine developers in deals worth up to nearly $4 billion in combined value

** LLY will buy Curevo for up to $1.5 billion in cash, LimmaTech Biologics for up to $780 million and Vaccine Company for up to $1.55 billion

** Curevo's lead product candidate is a shingles vaccine, LimmaTech Biologics is developing vaccines against certain bacterial pathogens that are difficult to treat

** Vaccine Company is developing a preventive shot for Epstein-Barr Virus

** All three deals are inclusive of an upfront payment and subsequent payments upon achievement of certain clinical and commercial milestones

** Up to last close, stock mostly flat YTD