Eli Lilly is acquiring three small vaccine developers, expanding its work in infectious diseases and giving the field a boost.

Worth close to $4 billion combined, the acquisitions of Curevo, LimmaTech and Vaccine Co. signal plans by Lilly to build an infectious disease portfolio.

The deals give Lilly vaccines targeting shingles, bacterial pathogens, and Epstein-Barr virus as it expands beyond weight loss drugs