Researchers have mapped the most common bacterial cause of pneumonia around the world and revealed how these bacteria evolve in response to vaccination. Scientists from the Wellcome Sanger Institute and their collaborators carried out a global genomic survey of Streptococcus pneumoniae, discovering 621 strains across more than fifty countries. Published in The Lancet Infectious Diseases, the study will help predict which strains will be important for new pneumococcal vaccines.